<?xml version="1.0" encoding="us-ascii"?>
<!-- DFS ActiveDisclosure(SM) XBRL Linkbase Document - http://www.dfsco.com/financial-services/ -->
<!-- Creation Date      : 2018-11-06T00:30:54.1275825+00:00 -->
<!-- Version            : 3.1.6852.22116 -->
<!-- Package ID         : 4e591bfac2344d3da0c647736a1294d2 -->
<!-- Copyright (c) 2018 Donnelley Financial, LLC. All Rights Reserved. -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" />
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" />
  <roleRef xlink:type="simple" xlink:href="gldd-20180930.xsd#TemplateLink" roleURI="http://www.gldd.com/20180930/role/TemplateLink" />
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/StatementCondensedConsolidatedStatementsOfEquity" xlink:href="gldd-20180930.xsd#Role_StatementCondensedConsolidatedStatementsOfEquity" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/StatementCondensedConsolidatedStatementsOfEquity">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" />
    <loc xlink:href="gldd-20180930.xsd#gldd_VestingOfRestrictedStockUnitsSharesIncludingImpactOfSharesWithheldForTaxes" xlink:type="locator" xlink:label="gldd_VestingOfRestrictedStockUnitsSharesIncludingImpactOfSharesWithheldForTaxes" />
    <loc xlink:href="gldd-20180930.xsd#gldd_VestingOfRestrictedStockUnitsValueIncludingImpactOfSharesWithheldForTaxes" xlink:type="locator" xlink:label="gldd_VestingOfRestrictedStockUnitsValueIncludingImpactOfSharesWithheldForTaxes" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesOutstanding" xlink:type="locator" xlink:label="us-gaap_SharesOutstanding" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember" xlink:type="locator" xlink:label="us-gaap_TreasuryStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:type="locator" xlink:label="us-gaap_CommonStockMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:type="locator" xlink:label="us-gaap_StatementTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:type="locator" xlink:label="us-gaap_StatementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_TreasuryStockMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquity" order="10420.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SharesOutstanding" order="10440.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification" order="10600.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" order="10780.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" order="10800.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="gldd_VestingOfRestrictedStockUnitsValueIncludingImpactOfSharesWithheldForTaxes" order="10960.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="gldd_VestingOfRestrictedStockUnitsSharesIncludingImpactOfSharesWithheldForTaxes" order="10980.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" order="11140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" order="11160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetIncomeLoss" order="11320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax" order="11500.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsParenthetical" xlink:href="gldd-20180930.xsd#Role_StatementCondensedConsolidatedStatementsOfCashFlowsParenthetical" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsParenthetical">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <loc xlink:href="gldd-20180930.xsd#gldd_SevenPointThreeSevenFiveSeniorNotesDueInTwoThousandNineteenMember" xlink:type="locator" xlink:label="gldd_SevenPointThreeSevenFiveSeniorNotesDueInTwoThousandNineteenMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:type="locator" xlink:label="us-gaap_StatementTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:type="locator" xlink:label="us-gaap_StatementLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_DebtInstrumentAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="gldd_SevenPointThreeSevenFiveSeniorNotesDueInTwoThousandNineteenMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" order="10120.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueTables" xlink:href="gldd-20180930.xsd#Role_DisclosureRevenueTables" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueTables">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostsInExcessOfBillingsAndBillingsInExcessOfCostsTableTextBlock" xlink:type="locator" xlink:label="us-gaap_CostsInExcessOfBillingsAndBillingsInExcessOfCostsTableTextBlock" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueTableTextBlock" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ScheduleOfCondensedIncomeStatementTableTextBlock" xlink:type="locator" xlink:label="srt_ScheduleOfCondensedIncomeStatementTableTextBlock" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ScheduleOfCondensedBalanceSheetTableTextBlock" xlink:type="locator" xlink:label="srt_ScheduleOfCondensedBalanceSheetTableTextBlock" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201409Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="locator" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RevenueRecognitionTable" xlink:type="locator" xlink:label="gldd_RevenueRecognitionTable" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RevenueRecognitionLineItems" xlink:type="locator" xlink:label="gldd_RevenueRecognitionLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="gldd_RevenueRecognitionTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_RevenueRecognitionTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201409Member" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="srt_ScheduleOfCondensedBalanceSheetTableTextBlock" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="srt_ScheduleOfCondensedIncomeStatementTableTextBlock" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_DisaggregationOfRevenueTableTextBlock" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_CostsInExcessOfBillingsAndBillingsInExcessOfCostsTableTextBlock" order="10440.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureBasisOfPresentationScheduleOfReconciliationOfCashCashEquivalentsAndRestrictedCashDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureBasisOfPresentationScheduleOfReconciliationOfCashCashEquivalentsAndRestrictedCashDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureBasisOfPresentationScheduleOfReconciliationOfCashCashEquivalentsAndRestrictedCashDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:type="locator" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:type="locator" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201618Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201618Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="locator" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OrganizationConsolidationAndPresentationTable" xlink:type="locator" xlink:label="gldd_OrganizationConsolidationAndPresentationTable" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OrganizationConsolidationAndPresentationLineItems" xlink:type="locator" xlink:label="gldd_OrganizationConsolidationAndPresentationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="gldd_OrganizationConsolidationAndPresentationTable" order="10030.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_OrganizationConsolidationAndPresentationTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201618Member" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" order="10280.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureBasisOfPresentationScheduleOfQuarterlyImpactOfChangeInAccountingPolicyOnCondensedConsolidatedStatementsOfOperationsAndCondensedConsolidatedBalanceSheetsDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureBasisOfPresentationScheduleOfQuarterlyImpactOfChangeInAccountingPolicyOnCondensedConsolidatedStatementsOfOperationsAndCondensedConsolidatedBalanceSheetsDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureBasisOfPresentationScheduleOfQuarterlyImpactOfChangeInAccountingPolicyOnCondensedConsolidatedStatementsOfOperationsAndCondensedConsolidatedBalanceSheetsDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperations" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:type="locator" xlink:label="us-gaap_CostOfGoodsAndServicesSold" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" xlink:type="locator" xlink:label="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201618Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201618Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="locator" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OrganizationConsolidationAndPresentationTable" xlink:type="locator" xlink:label="gldd_OrganizationConsolidationAndPresentationTable" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OrganizationConsolidationAndPresentationLineItems" xlink:type="locator" xlink:label="gldd_OrganizationConsolidationAndPresentationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="gldd_OrganizationConsolidationAndPresentationTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_OrganizationConsolidationAndPresentationTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201618Member" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_OrganizationConsolidationAndPresentationTable" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain_2" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:to="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_CostOfGoodsAndServicesSold" order="10620.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_IncomeTaxExpenseBenefit" order="10660.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_IncomeLossFromContinuingOperations" order="10700.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_NetIncomeLoss" order="10740.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_ComprehensiveIncomeNetOfTax" order="10780.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" order="10820.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" order="10860.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" order="10930.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_DeferredTaxLiabilitiesNoncurrent" order="10950.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" order="10970.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureBasisOfPresentationNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureBasisOfPresentationNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureBasisOfPresentationNarrativeDetails">
    <loc xlink:href="gldd-20180930.xsd#gldd_NumberOfReportableSegmentsWithGoodwill" xlink:type="locator" xlink:label="gldd_NumberOfReportableSegmentsWithGoodwill" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:type="locator" xlink:label="us-gaap_NumberOfReportableSegments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NumberOfOperatingSegments" xlink:type="locator" xlink:label="us-gaap_NumberOfOperatingSegments" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201409Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="locator" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OrganizationConsolidationAndPresentationTable" xlink:type="locator" xlink:label="gldd_OrganizationConsolidationAndPresentationTable" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OrganizationConsolidationAndPresentationLineItems" xlink:type="locator" xlink:label="gldd_OrganizationConsolidationAndPresentationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="gldd_OrganizationConsolidationAndPresentationTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_OrganizationConsolidationAndPresentationTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201409Member" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_NumberOfOperatingSegments" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="us-gaap_NumberOfReportableSegments" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_OrganizationConsolidationAndPresentationLineItems" xlink:to="gldd_NumberOfReportableSegmentsWithGoodwill" order="10210.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureLongTermDebtNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureLongTermDebtNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureLongTermDebtNarrativeDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SaleLeasebackTransactionNetProceedsFinancingActivities" xlink:type="locator" xlink:label="us-gaap_SaleLeasebackTransactionNetProceedsFinancingActivities" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:type="locator" xlink:label="us-gaap_LongTermDebtNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:type="locator" xlink:label="us-gaap_LongTermDebtCurrent" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OwnedDomesticSubsidiariesPercent" xlink:type="locator" xlink:label="gldd_OwnedDomesticSubsidiariesPercent" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RedemptionOfNotes" xlink:type="locator" xlink:label="gldd_RedemptionOfNotes" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromIssuanceOfDebt" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfDebt" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FaceValueOfSeniorNotesIssuedPercentage" xlink:type="locator" xlink:label="gldd_FaceValueOfSeniorNotesIssuedPercentage" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentMaturityDate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:type="locator" xlink:label="us-gaap_LettersOfCreditOutstandingAmount" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LinesOfCreditCurrent" xlink:type="locator" xlink:label="us-gaap_LinesOfCreditCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityExpirationDate1" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityExpirationDate1" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FixedChargeCoverageRatioTriggerForMaximumAvailabilityUnderCreditAgreementForOneDay" xlink:type="locator" xlink:label="gldd_FixedChargeCoverageRatioTriggerForMaximumAvailabilityUnderCreditAgreementForOneDay" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FixedChargeCoverageRatioTriggerForMaximumAvailabilityUnderCreditAgreementForFiveConsecutiveDays" xlink:type="locator" xlink:label="gldd_FixedChargeCoverageRatioTriggerForMaximumAvailabilityUnderCreditAgreementForFiveConsecutiveDays" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FixedChargeCoverageRatio" xlink:type="locator" xlink:label="gldd_FixedChargeCoverageRatio" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CapitalExpendituresByCreditParties" xlink:type="locator" xlink:label="gldd_CapitalExpendituresByCreditParties" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseExpense" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseExpense" />
    <loc xlink:href="gldd-20180930.xsd#gldd_LineOfCreditFacilityOptionalIncreaseCapacity" xlink:type="locator" xlink:label="gldd_LineOfCreditFacilityOptionalIncreaseCapacity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
    <loc xlink:href="gldd-20180930.xsd#gldd_VesselsAndAncillaryEquipmentMember" xlink:type="locator" xlink:label="gldd_VesselsAndAncillaryEquipmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:type="locator" xlink:label="us-gaap_SeniorNotesMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_SevenPointThreeSevenFiveSeniorNotesDueInTwoThousandNineteenMember" xlink:type="locator" xlink:label="gldd_SevenPointThreeSevenFiveSeniorNotesDueInTwoThousandNineteenMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EightPercentSeniorNotesDueInTwoThousandTwentyTwoMember" xlink:type="locator" xlink:label="gldd_EightPercentSeniorNotesDueInTwoThousandTwentyTwoMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:type="locator" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BaseRateMember" xlink:type="locator" xlink:label="us-gaap_BaseRateMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:type="locator" xlink:label="us-gaap_VariableRateDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:type="locator" xlink:label="us-gaap_VariableRateDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:type="locator" xlink:label="us-gaap_VariableRateAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:type="locator" xlink:label="us-gaap_ScenarioForecastMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:type="locator" xlink:label="srt_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:type="locator" xlink:label="srt_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember_2" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:type="locator" xlink:label="srt_RangeAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_SwinglineLoansMember" xlink:type="locator" xlink:label="gldd_SwinglineLoansMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StandbyLettersOfCreditMember" xlink:type="locator" xlink:label="us-gaap_StandbyLettersOfCreditMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:type="locator" xlink:label="us-gaap_RevolvingCreditFacilityMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:type="locator" xlink:label="us-gaap_CreditFacilityDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:type="locator" xlink:label="us-gaap_CreditFacilityDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:type="locator" xlink:label="us-gaap_CreditFacilityAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_CreditFacilityAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_RevolvingCreditFacilityMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_StandbyLettersOfCreditMember" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="gldd_SwinglineLoansMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="srt_RangeAxis" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_2" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_StatementScenarioAxis" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_2" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="us-gaap_ScenarioForecastMember" order="10310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_VariableRateAxis" order="10520.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain_2" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain" order="10550.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_BaseRateMember" order="10570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_LondonInterbankOfferedRateLIBORMember" order="10630.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" order="10840.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" order="10870.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="gldd_EightPercentSeniorNotesDueInTwoThousandTwentyTwoMember" order="10890.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="gldd_SevenPointThreeSevenFiveSeniorNotesDueInTwoThousandNineteenMember" order="10950.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_LongtermDebtTypeAxis" order="11020.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain_2" order="11030.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" order="11050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_SeniorNotesMember" order="11070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="gldd_VesselsAndAncillaryEquipmentMember" order="11210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" order="11280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_LineOfCreditFacilityOptionalIncreaseCapacity" order="11340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_OperatingLeaseExpense" order="11390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_CapitalExpendituresByCreditParties" order="11430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_FixedChargeCoverageRatio" order="11500.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_FixedChargeCoverageRatioTriggerForMaximumAvailabilityUnderCreditAgreementForFiveConsecutiveDays" order="11520.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_FixedChargeCoverageRatioTriggerForMaximumAvailabilityUnderCreditAgreementForOneDay" order="11540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityExpirationDate1" order="11560.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" order="11610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" order="11730.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LinesOfCreditCurrent" order="11800.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LettersOfCreditOutstandingAmount" order="11820.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" order="11840.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" order="11860.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" order="11910.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" order="11950.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentMaturityDate" order="11990.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_FaceValueOfSeniorNotesIssuedPercentage" order="12030.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfDebt" order="12070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_RedemptionOfNotes" order="12230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="gldd_OwnedDomesticSubsidiariesPercent" order="12300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebtCurrent" order="12350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebtNoncurrent" order="12390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_SaleLeasebackTransactionNetProceedsFinancingActivities" order="12430.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFairValuesOfFinancialInstrumentsAndNonfinancialAssetsAndLiabilitiesMeasuredAtReportingDateDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureFairValueMeasurementsScheduleOfFairValuesOfFinancialInstrumentsAndNonfinancialAssetsAndLiabilitiesMeasuredAtReportingDateDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFairValuesOfFinancialInstrumentsAndNonfinancialAssetsAndLiabilitiesMeasuredAtReportingDateDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueNetAssetLiability" xlink:type="locator" xlink:label="us-gaap_FairValueNetAssetLiability" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel3Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel2Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FuelHedgeContractsMember" xlink:type="locator" xlink:label="gldd_FuelHedgeContractsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:type="locator" xlink:label="us-gaap_HedgingRelationshipDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:type="locator" xlink:label="us-gaap_HedgingRelationshipDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:type="locator" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:type="locator" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="gldd_FuelHedgeContractsMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_FairValueNetAssetLiability" order="10380.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureFairValueMeasurementsNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsNarrativeDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFairValue" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentMaturityDate" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueHedgeAssetsAtFairValue" xlink:type="locator" xlink:label="us-gaap_FairValueHedgeAssetsAtFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeSwapTypeFixedPrice" xlink:type="locator" xlink:label="us-gaap_DerivativeSwapTypeFixedPrice" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountVolume" xlink:type="locator" xlink:label="us-gaap_DerivativeNonmonetaryNotionalAmountVolume" />
    <loc xlink:href="gldd-20180930.xsd#gldd_DerivativeUnderlyingHedgePercent" xlink:type="locator" xlink:label="gldd_DerivativeUnderlyingHedgePercent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EightPercentSeniorNotesDueInTwoThousandTwentyTwoMember" xlink:type="locator" xlink:label="gldd_EightPercentSeniorNotesDueInTwoThousandTwentyTwoMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseMember" xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpenseMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:type="locator" xlink:label="srt_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:type="locator" xlink:label="srt_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:type="locator" xlink:label="srt_RangeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:type="locator" xlink:label="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativesFairValueLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativesFairValueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="srt_RangeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_IncomeStatementLocationAxis" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain_2" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_OtherNonoperatingIncomeExpenseMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_DebtInstrumentAxis" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="gldd_EightPercentSeniorNotesDueInTwoThousandTwentyTwoMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="gldd_DerivativeUnderlyingHedgePercent" order="10420.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DerivativeNonmonetaryNotionalAmountVolume" order="10470.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DerivativeSwapTypeFixedPrice" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_FairValueHedgeAssetsAtFairValue" order="10680.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax" order="10720.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax" order="10790.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" order="10840.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" order="10880.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DebtInstrumentMaturityDate" order="11000.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_DebtInstrumentFairValue" order="11040.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFairValueOfFuelHedgeContractsBalanceSheetLocationDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureFairValueMeasurementsScheduleOfFairValueOfFuelHedgeContractsBalanceSheetLocationDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFairValueOfFuelHedgeContractsBalanceSheetLocationDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueHedgeAssetsAtFairValue" xlink:type="locator" xlink:label="us-gaap_FairValueHedgeAssetsAtFairValue" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FuelHedgeContractsMember" xlink:type="locator" xlink:label="gldd_FuelHedgeContractsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:type="locator" xlink:label="us-gaap_HedgingRelationshipDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:type="locator" xlink:label="us-gaap_DesignatedAsHedgingInstrumentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:type="locator" xlink:label="us-gaap_HedgingDesignationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:type="locator" xlink:label="us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:type="locator" xlink:label="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativesFairValueLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativesFairValueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_BalanceSheetLocationAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_HedgingDesignationAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_DesignatedAsHedgingInstrumentMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="gldd_FuelHedgeContractsMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativesFairValueLineItems" xlink:to="us-gaap_FairValueHedgeAssetsAtFairValue" order="10240.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsAdjustmentsReclassifiedFromAccumulatedBalancesOtherComprehensiveIncomeLossToEarningsDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureFairValueMeasurementsAdjustmentsReclassifiedFromAccumulatedBalancesOtherComprehensiveIncomeLossToEarningsDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureFairValueMeasurementsAdjustmentsReclassifiedFromAccumulatedBalancesOtherComprehensiveIncomeLossToEarningsDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:type="locator" xlink:label="us-gaap_CostOfGoodsAndServicesSold" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" xlink:type="locator" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:type="locator" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:type="locator" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:type="locator" xlink:label="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" xlink:type="locator" xlink:label="us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FuelHedgeContractsMember" xlink:type="locator" xlink:label="gldd_FuelHedgeContractsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:type="locator" xlink:label="us-gaap_HedgingRelationshipDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:type="locator" xlink:label="us-gaap_DerivativeInstrumentsGainLossLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" order="10030.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" order="10060.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="gldd_FuelHedgeContractsMember" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_2" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:to="us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_CostOfGoodsAndServicesSold" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_IncomeTaxExpenseBenefit" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeInstrumentsGainLossLineItems" xlink:to="us-gaap_NetIncomeLoss" order="10420.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureShareBasedCompensationNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureShareBasedCompensationNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureShareBasedCompensationNarrativeDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensation" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
    <loc xlink:href="gldd-20180930.xsd#gldd_TwoThousandSevenLongTermIncentivePlanMember" xlink:type="locator" xlink:label="gldd_TwoThousandSevenLongTermIncentivePlanMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_TwoThousandSeventeenLongTermIncentivePlanMember" xlink:type="locator" xlink:label="gldd_TwoThousandSeventeenLongTermIncentivePlanMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:type="locator" xlink:label="us-gaap_PlanNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:type="locator" xlink:label="us-gaap_PlanNameDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:type="locator" xlink:label="us-gaap_PlanNameAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EmployeesAndDirectorsMember" xlink:type="locator" xlink:label="gldd_EmployeesAndDirectorsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:type="locator" xlink:label="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:type="locator" xlink:label="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:type="locator" xlink:label="us-gaap_TitleOfIndividualAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_TitleOfIndividualAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_TitleOfIndividualAxis" xlink:to="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TitleOfIndividualAxis" xlink:to="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="gldd_EmployeesAndDirectorsMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_PlanNameAxis" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_2" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="gldd_TwoThousandSeventeenLongTermIncentivePlanMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="gldd_TwoThousandSevenLongTermIncentivePlanMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensation" order="10370.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfImpactOfChangeInAccountingPrincipleOnCondensedConsolidatedBalanceSheetsDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRevenueSummaryOfImpactOfChangeInAccountingPrincipleOnCondensedConsolidatedBalanceSheetsDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfImpactOfChangeInAccountingPrincipleOnCondensedConsolidatedBalanceSheetsDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BillingsInExcessOfCost" xlink:type="locator" xlink:label="us-gaap_BillingsInExcessOfCost" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_AccruedLiabilitiesCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsNoncurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsCurrent" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear" xlink:type="locator" xlink:label="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsAbstract" xlink:type="locator" xlink:label="us-gaap_AssetsAbstract" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" xlink:type="locator" xlink:label="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201409Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="locator" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201409Member" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:to="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_AssetsAbstract" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_OtherAssetsCurrent" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_OtherAssetsNoncurrent" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_AccruedLiabilitiesCurrent" order="10320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_BillingsInExcessOfCost" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_DeferredTaxLiabilitiesNoncurrent" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" order="10380.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfImpactOfChangeInAccountingPrincipleOnCondensedConsolidatedStatementsOfOperationsDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRevenueSummaryOfImpactOfChangeInAccountingPrincipleOnCondensedConsolidatedStatementsOfOperationsDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfImpactOfChangeInAccountingPrincipleOnCondensedConsolidatedStatementsOfOperationsDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperations" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperations" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfCostGoodOrServiceExtensibleList" xlink:type="locator" xlink:label="us-gaap_TypeOfCostGoodOrServiceExtensibleList" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:type="locator" xlink:label="us-gaap_CostOfGoodsAndServicesSold" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfRevenueExtensibleList" xlink:type="locator" xlink:label="us-gaap_TypeOfRevenueExtensibleList" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" xlink:type="locator" xlink:label="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201409Member" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:type="locator" xlink:label="us-gaap_TypeOfAdoptionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:type="locator" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201409Member" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:to="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_TypeOfRevenueExtensibleList" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_CostOfGoodsAndServicesSold" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_TypeOfCostGoodOrServiceExtensibleList" order="10340.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_IncomeTaxExpenseBenefit" order="10380.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_IncomeLossFromContinuingOperations" order="10420.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_NetIncomeLoss" order="10460.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:to="us-gaap_ComprehensiveIncomeNetOfTax" order="10500.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRevenueNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueNarrativeDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalizedContractCostAccumulatedAmortization" xlink:type="locator" xlink:label="us-gaap_CapitalizedContractCostAccumulatedAmortization" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalizedContractCostGross" xlink:type="locator" xlink:label="us-gaap_CapitalizedContractCostGross" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenuePerformanceObligationDescriptionOfTiming" xlink:type="locator" xlink:label="us-gaap_RevenuePerformanceObligationDescriptionOfTiming" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionYear1" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionYear1" />
    <loc xlink:href="gldd-20180930.xsd#gldd_PerformanceObligationExpectedToBeRecognizedAsRevenueYear" xlink:type="locator" xlink:label="gldd_PerformanceObligationExpectedToBeRecognizedAsRevenueYear" />
    <loc xlink:href="gldd-20180930.xsd#gldd_PercentageOfPerformanceObligationToBeRecognizedAsRevenue" xlink:type="locator" xlink:label="gldd_PercentageOfPerformanceObligationToBeRecognizedAsRevenue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligation" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OtherCurrentAndNoncurrentAssetsMember" xlink:type="locator" xlink:label="gldd_OtherCurrentAndNoncurrentAssetsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_ForeignMember" xlink:type="locator" xlink:label="gldd_ForeignMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:type="locator" xlink:label="srt_SegmentGeographicalDomain" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:type="locator" xlink:label="srt_SegmentGeographicalDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:type="locator" xlink:label="srt_StatementGeographicalAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_DredgingMember" xlink:type="locator" xlink:label="gldd_DredgingMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RevenueRecognitionTable" xlink:type="locator" xlink:label="gldd_RevenueRecognitionTable" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RevenueRecognitionLineItems" xlink:type="locator" xlink:label="gldd_RevenueRecognitionLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="gldd_RevenueRecognitionTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_RevenueRecognitionTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_DredgingMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_RevenueRecognitionTable" xlink:to="srt_StatementGeographicalAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="gldd_ForeignMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_RevenueRecognitionTable" xlink:to="us-gaap_BalanceSheetLocationAxis" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="gldd_OtherCurrentAndNoncurrentAssetsMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_RevenueRemainingPerformanceObligation" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="gldd_PercentageOfPerformanceObligationToBeRecognizedAsRevenue" order="10260.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="gldd_PerformanceObligationExpectedToBeRecognizedAsRevenueYear" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionYear1" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_RevenuePerformanceObligationDescriptionOfTiming" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_CapitalizedContractCostGross" order="10510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_RevenueRecognitionLineItems" xlink:to="us-gaap_CapitalizedContractCostAccumulatedAmortization" order="10550.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfSegmentAndTypeOfWorkContractRevenuesDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRevenueSummaryOfSegmentAndTypeOfWorkContractRevenuesDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfSegmentAndTypeOfWorkContractRevenuesDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RiversLakesMember" xlink:type="locator" xlink:label="gldd_RiversLakesMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_MaintenanceDredgingMember" xlink:type="locator" xlink:label="gldd_MaintenanceDredgingMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_BeachNourishmentDredgingMember" xlink:type="locator" xlink:label="gldd_BeachNourishmentDredgingMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CapitalDredgingForeignMember" xlink:type="locator" xlink:label="gldd_CapitalDredgingForeignMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CapitalDredgingUSMember" xlink:type="locator" xlink:label="gldd_CapitalDredgingUSMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:type="locator" xlink:label="srt_ProductsAndServicesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:type="locator" xlink:label="srt_ProductsAndServicesDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:type="locator" xlink:label="srt_ProductOrServiceAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EnvironmentalAndInfrastructureSegmentMember" xlink:type="locator" xlink:label="gldd_EnvironmentalAndInfrastructureSegmentMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_DredgingMember" xlink:type="locator" xlink:label="gldd_DredgingMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:type="locator" xlink:label="us-gaap_IntersegmentEliminationMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:type="locator" xlink:label="us-gaap_OperatingSegmentsMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:type="locator" xlink:label="srt_ConsolidationItemsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:type="locator" xlink:label="srt_ConsolidationItemsDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:type="locator" xlink:label="srt_ConsolidationItemsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_TypeOfWorkMember" xlink:type="locator" xlink:label="gldd_TypeOfWorkMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsegmentsDomain" xlink:type="locator" xlink:label="us-gaap_SubsegmentsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsegmentsDomain" xlink:type="locator" xlink:label="us-gaap_SubsegmentsDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsegmentsAxis" xlink:type="locator" xlink:label="us-gaap_SubsegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_SubsegmentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="gldd_TypeOfWorkMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="srt_ConsolidationItemsAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_IntersegmentEliminationMember" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10300.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_DredgingMember" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_EnvironmentalAndInfrastructureSegmentMember" order="10470.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="srt_ProductOrServiceAxis" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_2" order="10490.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" order="10510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="gldd_CapitalDredgingUSMember" order="10530.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="gldd_CapitalDredgingForeignMember" order="10550.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="gldd_BeachNourishmentDredgingMember" order="10570.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="gldd_MaintenanceDredgingMember" order="10590.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="gldd_RiversLakesMember" order="10610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" order="10640.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfSegmentAndTypeOfCustomerContractRevenuesDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRevenueSummaryOfSegmentAndTypeOfCustomerContractRevenuesDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueSummaryOfSegmentAndTypeOfCustomerContractRevenuesDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OtherMember" xlink:type="locator" xlink:label="gldd_OtherMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_ForeignMember" xlink:type="locator" xlink:label="gldd_ForeignMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_PrivateMember" xlink:type="locator" xlink:label="gldd_PrivateMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_StateAndLocalGovernmentMember" xlink:type="locator" xlink:label="gldd_StateAndLocalGovernmentMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_FederalGovernmentMember" xlink:type="locator" xlink:label="gldd_FederalGovernmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:type="locator" xlink:label="srt_SegmentGeographicalDomain" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:type="locator" xlink:label="srt_StatementGeographicalAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EnvironmentalAndInfrastructureSegmentMember" xlink:type="locator" xlink:label="gldd_EnvironmentalAndInfrastructureSegmentMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_DredgingMember" xlink:type="locator" xlink:label="gldd_DredgingMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:type="locator" xlink:label="us-gaap_IntersegmentEliminationMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:type="locator" xlink:label="us-gaap_OperatingSegmentsMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:type="locator" xlink:label="srt_ConsolidationItemsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:type="locator" xlink:label="srt_ConsolidationItemsAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_TypeOfCustomerMember" xlink:type="locator" xlink:label="gldd_TypeOfCustomerMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsegmentsDomain" xlink:type="locator" xlink:label="us-gaap_SubsegmentsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsegmentsAxis" xlink:type="locator" xlink:label="us-gaap_SubsegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_SubsegmentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="gldd_TypeOfCustomerMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="srt_ConsolidationItemsAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_IntersegmentEliminationMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_DredgingMember" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_EnvironmentalAndInfrastructureSegmentMember" order="10310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DisaggregationOfRevenueTable" xlink:to="srt_StatementGeographicalAxis" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" order="10390.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="gldd_FederalGovernmentMember" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="gldd_StateAndLocalGovernmentMember" order="10430.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="gldd_PrivateMember" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="gldd_ForeignMember" order="10470.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="gldd_OtherMember" order="10510.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" order="10540.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueComponentsOfContractsInProgressDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRevenueComponentsOfContractsInProgressDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRevenueComponentsOfContractsInProgressDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BillingsInExcessOfCost" xlink:type="locator" xlink:label="us-gaap_BillingsInExcessOfCost" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedAfterOneYear" xlink:type="locator" xlink:label="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedAfterOneYear" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear" xlink:type="locator" xlink:label="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms" xlink:type="locator" xlink:label="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CostsAndEarningsInExcessOfBillingsForCompletedContracts" xlink:type="locator" xlink:label="gldd_CostsAndEarningsInExcessOfBillingsForCompletedContracts" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CostsAndEarningsInExcessOfBillingsForContractsInProgress" xlink:type="locator" xlink:label="gldd_CostsAndEarningsInExcessOfBillingsForContractsInProgress" />
    <loc xlink:href="gldd-20180930.xsd#gldd_BillingsForContractsInProgress" xlink:type="locator" xlink:label="gldd_BillingsForContractsInProgress" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CostsAndEarningsForContractsInProgress" xlink:type="locator" xlink:label="gldd_CostsAndEarningsForContractsInProgress" />
    <loc xlink:href="gldd-20180930.xsd#gldd_BillingsInExcessOfCostsAndEarningsMember" xlink:type="locator" xlink:label="gldd_BillingsInExcessOfCostsAndEarningsMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CostsAndEarningsInExcessOfBillingsMember" xlink:type="locator" xlink:label="gldd_CostsAndEarningsInExcessOfBillingsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReceivableTypeDomain" xlink:type="locator" xlink:label="us-gaap_ReceivableTypeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReceivableTypeDomain" xlink:type="locator" xlink:label="us-gaap_ReceivableTypeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:type="locator" xlink:label="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:type="locator" xlink:label="us-gaap_AccountsNotesAndLoansReceivableLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" order="10070.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:to="us-gaap_ReceivableTypeDomain_2" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:to="us-gaap_ReceivableTypeDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ReceivableTypeDomain" xlink:to="gldd_CostsAndEarningsInExcessOfBillingsMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ReceivableTypeDomain" xlink:to="gldd_BillingsInExcessOfCostsAndEarningsMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="gldd_CostsAndEarningsForContractsInProgress" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="gldd_BillingsForContractsInProgress" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="gldd_CostsAndEarningsInExcessOfBillingsForContractsInProgress" order="10320.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="gldd_CostsAndEarningsInExcessOfBillingsForCompletedContracts" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedWithinOneYear" order="10440.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrProgramsExpectedToBeCollectedAfterOneYear" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_BillingsInExcessOfCost" order="10640.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRestructuringChargesNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRestructuringChargesNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRestructuringChargesNarrativeDetails">
    <loc xlink:href="gldd-20180930.xsd#gldd_NumberOfVesselsRelatedToLeaseBuyout" xlink:type="locator" xlink:label="gldd_NumberOfVesselsRelatedToLeaseBuyout" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeveranceCosts1" xlink:type="locator" xlink:label="us-gaap_SeveranceCosts1" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedRentCurrentAndNoncurrent" xlink:type="locator" xlink:label="us-gaap_AccruedRentCurrentAndNoncurrent" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RestructuringAndRelatedCostExpectedCostNoncash" xlink:type="locator" xlink:label="gldd_RestructuringAndRelatedCostExpectedCostNoncash" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringAndRelatedCostExpectedCost1" xlink:type="locator" xlink:label="us-gaap_RestructuringAndRelatedCostExpectedCost1" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OtherItemsMember" xlink:type="locator" xlink:label="gldd_OtherItemsMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_LossOnSaleOfAssetsMember" xlink:type="locator" xlink:label="gldd_LossOnSaleOfAssetsMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_DepreciationMember" xlink:type="locator" xlink:label="gldd_DepreciationMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:type="locator" xlink:label="srt_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:type="locator" xlink:label="srt_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:type="locator" xlink:label="srt_RangeAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CloseoutCostsMember" xlink:type="locator" xlink:label="gldd_CloseoutCostsMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_PrecontractCostsMember" xlink:type="locator" xlink:label="gldd_PrecontractCostsMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_AssetRetirementsMember" xlink:type="locator" xlink:label="gldd_AssetRetirementsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:type="locator" xlink:label="us-gaap_EmployeeSeveranceMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:type="locator" xlink:label="us-gaap_TypeOfRestructuringDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:type="locator" xlink:label="us-gaap_TypeOfRestructuringDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:type="locator" xlink:label="us-gaap_RestructuringCostAndReserveAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:type="locator" xlink:label="us-gaap_RestructuringCostAndReserveLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_RestructuringCostAndReserveAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RestructuringCostAndReserveAxis" xlink:to="us-gaap_TypeOfRestructuringDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringCostAndReserveAxis" xlink:to="us-gaap_TypeOfRestructuringDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="us-gaap_EmployeeSeveranceMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="gldd_AssetRetirementsMember" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="gldd_PrecontractCostsMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfRestructuringDomain" xlink:to="gldd_CloseoutCostsMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="srt_RangeAxis" order="10200.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_IncomeStatementLocationAxis" order="10560.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" order="10590.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="gldd_DepreciationMember" order="10610.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="gldd_LossOnSaleOfAssetsMember" order="10650.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="gldd_OtherItemsMember" order="10690.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_RestructuringAndRelatedCostExpectedCost1" order="10740.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="gldd_RestructuringAndRelatedCostExpectedCostNoncash" order="10930.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_AccruedRentCurrentAndNoncurrent" order="11120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_SeveranceCosts1" order="11160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="gldd_NumberOfVesselsRelatedToLeaseBuyout" order="11200.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureRestructuringChargesScheduleOfRestructuringChargesDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureRestructuringChargesScheduleOfRestructuringChargesDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureRestructuringChargesScheduleOfRestructuringChargesDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCharges" xlink:type="locator" xlink:label="us-gaap_RestructuringCharges" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseMember" xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpenseMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_LossOnSaleOfAssetsNetMember" xlink:type="locator" xlink:label="gldd_LossOnSaleOfAssetsNetMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:type="locator" xlink:label="us-gaap_GeneralAndAdministrativeExpenseMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CostsOfContractRevenuesOtherMember" xlink:type="locator" xlink:label="gldd_CostsOfContractRevenuesOtherMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CostsOfContractRevenuesDepreciationMember" xlink:type="locator" xlink:label="gldd_CostsOfContractRevenuesDepreciationMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EnvironmentalAndInfrastructureSegmentMember" xlink:type="locator" xlink:label="gldd_EnvironmentalAndInfrastructureSegmentMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_DredgingSegmentMember" xlink:type="locator" xlink:label="gldd_DredgingSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:type="locator" xlink:label="us-gaap_RestructuringCostAndReserveLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_DredgingSegmentMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_EnvironmentalAndInfrastructureSegmentMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_IncomeStatementLocationAxis" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="gldd_CostsOfContractRevenuesDepreciationMember" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="gldd_CostsOfContractRevenuesOtherMember" order="10310.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_GeneralAndAdministrativeExpenseMember" order="10330.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="gldd_LossOnSaleOfAssetsNetMember" order="10350.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_OtherNonoperatingIncomeExpenseMember" order="10370.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_RestructuringCharges" order="10520.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureCommitmentsAndContingenciesNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureCommitmentsAndContingenciesNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureCommitmentsAndContingenciesNarrativeDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLegalSettlements" xlink:type="locator" xlink:label="us-gaap_ProceedsFromLegalSettlements" />
    <loc xlink:href="gldd-20180930.xsd#gldd_WarrantyPeriods" xlink:type="locator" xlink:label="gldd_WarrantyPeriods" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:type="locator" xlink:label="us-gaap_LossContingencyDamagesSoughtValue" />
    <loc xlink:href="gldd-20180930.xsd#gldd_RevenueValueRemainingFromOutstandingPerformanceBonds" xlink:type="locator" xlink:label="gldd_RevenueValueRemainingFromOutstandingPerformanceBonds" />
    <loc xlink:href="gldd-20180930.xsd#gldd_OutstandingPerformanceBonds" xlink:type="locator" xlink:label="gldd_OutstandingPerformanceBonds" />
    <loc xlink:href="gldd-20180930.xsd#gldd_BidsBondRange" xlink:type="locator" xlink:label="gldd_BidsBondRange" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SuretyBondMember" xlink:type="locator" xlink:label="us-gaap_SuretyBondMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:type="locator" xlink:label="us-gaap_LossContingencyNatureDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:type="locator" xlink:label="us-gaap_LossContingencyNatureDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:type="locator" xlink:label="us-gaap_LossContingenciesByNatureOfContingencyAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:type="locator" xlink:label="us-gaap_LetterOfCreditMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:type="locator" xlink:label="us-gaap_CreditFacilityDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:type="locator" xlink:label="us-gaap_CreditFacilityAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EnvironmentalAndInfrastructureSegmentMember" xlink:type="locator" xlink:label="gldd_EnvironmentalAndInfrastructureSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:type="locator" xlink:label="srt_MaximumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:type="locator" xlink:label="srt_MinimumMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:type="locator" xlink:label="srt_RangeAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CommitmentsAndContingenciesTable" xlink:type="locator" xlink:label="gldd_CommitmentsAndContingenciesTable" />
    <loc xlink:href="gldd-20180930.xsd#gldd_CommitmentsAndContingenciesLineItems" xlink:type="locator" xlink:label="gldd_CommitmentsAndContingenciesLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="gldd_CommitmentsAndContingenciesTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_CommitmentsAndContingenciesTable" xlink:to="srt_RangeAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" order="10110.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_CommitmentsAndContingenciesTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10120.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_EnvironmentalAndInfrastructureSegmentMember" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_CommitmentsAndContingenciesTable" xlink:to="us-gaap_CreditFacilityAxis" order="10180.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_LetterOfCreditMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="gldd_CommitmentsAndContingenciesTable" xlink:to="us-gaap_LossContingenciesByNatureOfContingencyAxis" order="10240.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:to="us-gaap_LossContingencyNatureDomain_2" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:to="us-gaap_LossContingencyNatureDomain" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingencyNatureDomain" xlink:to="us-gaap_SuretyBondMember" order="10290.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="gldd_BidsBondRange" order="10400.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="gldd_OutstandingPerformanceBonds" order="10480.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="gldd_RevenueValueRemainingFromOutstandingPerformanceBonds" order="10560.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_LossContingencyDamagesSoughtValue" order="10670.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" order="10690.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="gldd_WarrantyPeriods" order="10740.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="gldd_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_ProceedsFromLegalSettlements" order="10830.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureInvestmentsDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureInvestmentsDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureInvestmentsDetails">
    <loc xlink:href="gldd-20180930.xsd#gldd_LossFromFundingToJointVenture" xlink:type="locator" xlink:label="gldd_LossFromFundingToJointVenture" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:type="locator" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage" />
    <loc xlink:href="gldd-20180930.xsd#gldd_TerraseaEnvironmentalSolutionsMember" xlink:type="locator" xlink:label="gldd_TerraseaEnvironmentalSolutionsMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_EquityMethodInvesteeNameDomain" xlink:type="locator" xlink:label="srt_EquityMethodInvesteeNameDomain" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_EquityMethodInvesteeNameDomain" xlink:type="locator" xlink:label="srt_EquityMethodInvesteeNameDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:type="locator" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:to="us-gaap_ScheduleOfEquityMethodInvestmentsTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="gldd_TerraseaEnvironmentalSolutionsMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:to="gldd_LossFromFundingToJointVenture" order="10160.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureBusinessCombinationsAndDispositionsNarrativeDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureBusinessCombinationsAndDispositionsNarrativeDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureBusinessCombinationsAndDispositionsNarrativeDetails">
    <loc xlink:href="gldd-20180930.xsd#gldd_MaximumPotentialAggregateEarnoutPayment" xlink:type="locator" xlink:label="gldd_MaximumPotentialAggregateEarnoutPayment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFairValue" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFairValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsForPreviousAcquisition" xlink:type="locator" xlink:label="us-gaap_PaymentsForPreviousAcquisition" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts" />
    <loc xlink:href="gldd-20180930.xsd#gldd_LossContingencyDamagesSoughtEstimatedValue" xlink:type="locator" xlink:label="gldd_LossContingencyDamagesSoughtEstimatedValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:type="locator" xlink:label="us-gaap_LossContingencyDamagesSoughtValue" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromDivestitureOfBusinesses" xlink:type="locator" xlink:label="us-gaap_ProceedsFromDivestitureOfBusinesses" />
    <loc xlink:href="gldd-20180930.xsd#gldd_GreatLakesEnvironmentalAndInfrastructureLLCMember" xlink:type="locator" xlink:label="gldd_GreatLakesEnvironmentalAndInfrastructureLLCMember" />
    <loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:type="locator" xlink:label="dei_EntityDomain" />
    <loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:type="locator" xlink:label="dei_EntityDomain_2" />
    <loc xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:type="locator" xlink:label="dei_LegalEntityAxis" />
    <loc xlink:href="gldd-20180930.xsd#gldd_MagnusPacificAcquisitionMember" xlink:type="locator" xlink:label="gldd_MagnusPacificAcquisitionMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SuretyBondMember" xlink:type="locator" xlink:label="us-gaap_SuretyBondMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:type="locator" xlink:label="us-gaap_LossContingencyNatureDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:type="locator" xlink:label="us-gaap_LossContingenciesByNatureOfContingencyAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDiscontinuedOperationsMember" xlink:type="locator" xlink:label="us-gaap_SegmentDiscontinuedOperationsMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentOperatingActivitiesDomain" xlink:type="locator" xlink:label="us-gaap_SegmentOperatingActivitiesDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentOperatingActivitiesDomain" xlink:type="locator" xlink:label="us-gaap_SegmentOperatingActivitiesDomain_2" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis" xlink:type="locator" xlink:label="us-gaap_StatementOperatingActivitiesSegmentAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_StatementOperatingActivitiesSegmentAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementOperatingActivitiesSegmentAxis" xlink:to="us-gaap_SegmentOperatingActivitiesDomain_2" order="10050.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementOperatingActivitiesSegmentAxis" xlink:to="us-gaap_SegmentOperatingActivitiesDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentOperatingActivitiesDomain" xlink:to="us-gaap_SegmentDiscontinuedOperationsMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_LossContingenciesByNatureOfContingencyAxis" order="10100.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:to="us-gaap_LossContingencyNatureDomain" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LossContingencyNatureDomain" xlink:to="us-gaap_SuretyBondMember" order="10150.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_BusinessAcquisitionAxis" order="10160.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain_2" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="gldd_MagnusPacificAcquisitionMember" order="10210.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="dei_LegalEntityAxis" order="10220.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_2" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" order="10250.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="gldd_GreatLakesEnvironmentalAndInfrastructureLLCMember" order="10270.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_ProceedsFromDivestitureOfBusinesses" order="10360.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_LossContingencyDamagesSoughtValue" order="10410.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="gldd_LossContingencyDamagesSoughtEstimatedValue" order="10450.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts" order="10520.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_PaymentsForPreviousAcquisition" order="10540.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_DebtInstrumentFairValue" order="10590.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="gldd_MaximumPotentialAggregateEarnoutPayment" order="10630.00" priority="2" use="optional" />
  </definitionLink>
  <roleRef roleURI="http://www.gldd.com/20180930/taxonomy/role/DisclosureSegmentInformationSegmentReportingBySegmentDetails" xlink:href="gldd-20180930.xsd#Role_DisclosureSegmentInformationSegmentReportingBySegmentDetails" xlink:type="simple" />
  <definitionLink xlink:type="extended" xlink:role="http://www.gldd.com/20180930/taxonomy/role/DisclosureSegmentInformationSegmentReportingBySegmentDetails">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <loc xlink:href="gldd-20180930.xsd#gldd_EnvironmentalAndInfrastructureSegmentMember" xlink:type="locator" xlink:label="gldd_EnvironmentalAndInfrastructureSegmentMember" />
    <loc xlink:href="gldd-20180930.xsd#gldd_DredgingSegmentMember" xlink:type="locator" xlink:label="gldd_DredgingSegmentMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:type="locator" xlink:label="us-gaap_IntersegmentEliminationMember" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:type="locator" xlink:label="us-gaap_OperatingSegmentsMember" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:type="locator" xlink:label="srt_ConsolidationItemsDomain" />
    <loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:type="locator" xlink:label="srt_ConsolidationItemsAxis" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingInformationLineItems" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" order="10010.00" priority="2" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="srt_ConsolidationItemsAxis" order="10040.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" order="10070.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_OperatingSegmentsMember" order="10090.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_IntersegmentEliminationMember" order="10130.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_StatementBusinessSegmentsAxis" order="10140.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_SegmentDomain" order="10170.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_DredgingSegmentMember" order="10190.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentDomain" xlink:to="gldd_EnvironmentalAndInfrastructureSegmentMember" order="10230.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" order="10280.00" priority="2" use="optional" />
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_OperatingIncomeLoss" order="10360.00" priority="2" use="optional" />
  </definitionLink>
</linkbase>
