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<!-- RR Donnelley Xcelerate Taxonomy Schema, based on XBRL 2.1  http://www.rrdonnelley.com/ -->
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<!-- Round: 5 -->
<!-- Creation date: 2013-11-08T17:52:01Z -->
<!-- Copyright (c) 2005-2013 R.R. Donnelley &amp; Sons Company All Rights Reserved. -->
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        <link:definition>133 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share, in Money Potential Common Shares (Detail)</link:definition>
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        <link:definition>134 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share, Out of Money Potential Common Shares (Detail)</link:definition>
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        <link:definition>135 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share, Out of Money Potential Common Shares (Parenthetical) (Detail)</link:definition>
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        <link:definition>136 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share, Convertible Preferred Stock (Detail)</link:definition>
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        <link:definition>137 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share, Unvested Restricted Stock Awards (Detail)</link:definition>
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  <element name="DerivativeFinancialInstrumentsFairValueAssumptionsContractualInterestRate" id="omex_DerivativeFinancialInstrumentsFairValueAssumptionsContractualInterestRate" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DerivativeFinancialInstrumentsFairValueAssumptionsCreditRiskAdjustedYieldRateRangeOfRates" id="omex_DerivativeFinancialInstrumentsFairValueAssumptionsCreditRiskAdjustedYieldRateRangeOfRates" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DerivativeFinancialInstrumentsFairValueAssumptionsLinkedCommonShares" id="omex_DerivativeFinancialInstrumentsFairValueAssumptionsLinkedCommonShares" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DerivativeFinancialInstrumentsFairValueAssumptionsMarketRiskAdjustedRateRangeOfRates" id="omex_DerivativeFinancialInstrumentsFairValueAssumptionsMarketRiskAdjustedRateRangeOfRates" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DerivativeFinancialInstrumentsFairValueAssumptionsQuotedMarketPrice" id="omex_DerivativeFinancialInstrumentsFairValueAssumptionsQuotedMarketPrice" type="num:perShareItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DerivativeFinancialInstrumentsFairValueAssumptionsTermInYears" id="omex_DerivativeFinancialInstrumentsFairValueAssumptionsTermInYears" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DerivativeFinancialInstrumentsFairValueContractualTermToMaturity" id="omex_DerivativeFinancialInstrumentsFairValueContractualTermToMaturity" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DerivativeIncomeExpenseNet" id="omex_DerivativeIncomeExpenseNet" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DistributionRatioOfRemainingNetProceed" id="omex_DistributionRatioOfRemainingNetProceed" type="xbrli:pureItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DividendsReceivedFromSubsidiary" id="omex_DividendsReceivedFromSubsidiary" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DocumentAndEntityInformationAbstract" id="omex_DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="DoradoOceanResourcesLimitedMember" id="omex_DoradoOceanResourcesLimitedMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EffectiveIncomeTaxRateReconciliationAlternateMinimumTaxCreditAmount" id="omex_EffectiveIncomeTaxRateReconciliationAlternateMinimumTaxCreditAmount" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EligibleEmployeeThresholdPercentage" id="omex_EligibleEmployeeThresholdPercentage" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EmployeeStockOptionsExercisePrice" id="omex_EmployeeStockOptionsExercisePrice" type="num:perShareItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EquityMethodInvestmentsNumberOfMembershipUnit" id="omex_EquityMethodInvestmentsNumberOfMembershipUnit" type="xbrli:integerItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EquityMethodInvestmentsSharesAcquired" id="omex_EquityMethodInvestmentsSharesAcquired" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EquityMethodInvestmentsSharesExchangeRatio" id="omex_EquityMethodInvestmentsSharesExchangeRatio" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="EquityMethodInvestmentsSharesOwned" id="omex_EquityMethodInvestmentsSharesOwned" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ExhibitRevenue" id="omex_ExhibitRevenue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ExpeditionCharterRevenue" id="omex_ExpeditionCharterRevenue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ExtinguishmentLossMember" id="omex_ExtinguishmentLossMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FairValueAssumptionVolatilityRangeAbstract" id="omex_FairValueAssumptionVolatilityRangeAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FederalOperatingLossCarryforwardsExpirationPeriodEnd" id="omex_FederalOperatingLossCarryforwardsExpirationPeriodEnd" type="xbrli:gYearItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FederalOperatingLossCarryforwardsExpirationPeriodStart" id="omex_FederalOperatingLossCarryforwardsExpirationPeriodStart" type="xbrli:gYearItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FixedPriceSwapFirstContractMember" id="omex_FixedPriceSwapFirstContractMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FixedPriceSwapMember" id="omex_FixedPriceSwapMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="FixedPriceSwapSecondContractMember" id="omex_FixedPriceSwapSecondContractMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="GairsoppaMember" id="omex_GairsoppaMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="GaltResourcesLlcHmsVictoryMember" id="omex_GaltResourcesLlcHmsVictoryMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="GaltResourcesLlcMember" id="omex_GaltResourcesLlcMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="HmsVictoryProjectMember" id="omex_HmsVictoryProjectMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxesLineItems" id="omex_IncomeTaxesLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxesTable" id="omex_IncomeTaxesTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem"/>
  <element name="IncomeTaxReconciliationChangeInApportionmentEstimate" id="omex_IncomeTaxReconciliationChangeInApportionmentEstimate" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxReconciliationChangeInCapitalLossCarryoverEstimate" id="omex_IncomeTaxReconciliationChangeInCapitalLossCarryoverEstimate" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxReconciliationChangeInNetOperatingLossEstimate" id="omex_IncomeTaxReconciliationChangeInNetOperatingLossEstimate" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxReconciliationDeductionsDerivatives" id="omex_IncomeTaxReconciliationDeductionsDerivatives" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxReconciliationDeductionsStockOptions" id="omex_IncomeTaxReconciliationDeductionsStockOptions" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxReconciliationGainLossOnSaleOfSubsidiaryStock" id="omex_IncomeTaxReconciliationGainLossOnSaleOfSubsidiaryStock" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxReconciliationIncomeTaxExpenseBenefitAtAlternativeMinimumTaxRate" id="omex_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtAlternativeMinimumTaxRate" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncrementalPercentageOfOriginalValue" id="omex_IncrementalPercentageOfOriginalValue" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IndebtednessInterestRatePerYear" id="omex_IndebtednessInterestRatePerYear" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IndebtednessInterestRatePerYearUnderDefaultCondition" id="omex_IndebtednessInterestRatePerYearUnderDefaultCondition" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InMoneyPotentialCommonSharesMember" id="omex_InMoneyPotentialCommonSharesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InterestObligationFromBasisPointVariation" id="omex_InterestObligationFromBasisPointVariation" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InventoryCurrentAndNonCurrentNet" id="omex_InventoryCurrentAndNonCurrentNet" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentForFutureRevenueRights" id="omex_InvestmentForFutureRevenueRights" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentInConsolidatedEntity" id="omex_InvestmentInConsolidatedEntity" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentInWhollyOwnedSubsidiary" id="omex_InvestmentInWhollyOwnedSubsidiary" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentMultiplierInCaseOfProjectSuccess" id="omex_InvestmentMultiplierInCaseOfProjectSuccess" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentRepaymentPeriod" id="omex_InvestmentRepaymentPeriod" type="xbrli:durationItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentsDebtAndEquitySecuritiesPolicyTextBlock" id="omex_InvestmentsDebtAndEquitySecuritiesPolicyTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IssuedWarrantsToAcquireCommonShares" id="omex_IssuedWarrantsToAcquireCommonShares" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="LenderMember" id="omex_LenderMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MarineServiceAccountReceivables" id="omex_MarineServiceAccountReceivables" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MarineServicesObligationsDeferredRevenue" id="omex_MarineServicesObligationsDeferredRevenue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MarketingGeneralAndAdministrativeExpenses" id="omex_MarketingGeneralAndAdministrativeExpenses" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaturityPeriodOfConcentrationOfCreditRisk" id="omex_MaturityPeriodOfConcentrationOfCreditRisk" type="xbrli:gYearMonthItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaximumIssueOfWarrantsToPurchaseCommonStock" id="omex_MaximumIssueOfWarrantsToPurchaseCommonStock" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaximumLoanToValuePercentage" id="omex_MaximumLoanToValuePercentage" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaximumPercentageOfCashFlowEffectOnPresentValueBasis" id="omex_MaximumPercentageOfCashFlowEffectOnPresentValueBasis" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaximumVotingRightPercentage" id="omex_MaximumVotingRightPercentage" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MineralExplorationArea" id="omex_MineralExplorationArea" type="xbrli:integerItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MinimumAmountOfAttorneyFeesClaimFiled" id="omex_MinimumAmountOfAttorneyFeesClaimFiled" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MinimumExpectedMonetizeAmount" id="omex_MinimumExpectedMonetizeAmount" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MiningExploratoryServiceRevenue" id="omex_MiningExploratoryServiceRevenue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MonteCarloSimulationsMember" id="omex_MonteCarloSimulationsMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MonthlyIncreaseOfRedemptionPrice" id="omex_MonthlyIncreaseOfRedemptionPrice" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableCurrent" id="omex_MortgageAndLoansPayableCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableCurrentAndNonCurrent" id="omex_MortgageAndLoansPayableCurrentAndNonCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableNonCurrent" id="omex_MortgageAndLoansPayableNonCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableTextBlock" id="omex_MortgageAndLoansPayableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NeptuneMineralsIncorporatedMember" id="omex_NeptuneMineralsIncorporatedMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NetIncomeLossAvailableToCommonStockholdersBasicAndDiluted" id="omex_NetIncomeLossAvailableToCommonStockholdersBasicAndDiluted" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NinePercentageConvertibleSeniorNotePayableMember" id="omex_NinePercentageConvertibleSeniorNotePayableMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NoncancelableObligationsFutureMinimumPaymentsDueLineItems" id="omex_NoncancelableObligationsFutureMinimumPaymentsDueLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfAccreditedInvestorsToWhomCommonStockIssued" id="omex_NumberOfAccreditedInvestorsToWhomCommonStockIssued" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfFinancialInstitutionsInWhichCashDeposited" id="omex_NumberOfFinancialInstitutionsInWhichCashDeposited" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfInstitutionalInvestorUnderSecuritiesPurchaseAgreement" id="omex_NumberOfInstitutionalInvestorUnderSecuritiesPurchaseAgreement" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfPreferredShareholdersConsideredForSeparateAgreementToIssueWarrants" id="omex_NumberOfPreferredShareholdersConsideredForSeparateAgreementToIssueWarrants" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfProjectsAfterBifurcation" id="omex_NumberOfProjectsAfterBifurcation" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfSecuritiesCalledByWarrantsOrRightsUponAdditionalFinancing" id="omex_NumberOfSecuritiesCalledByWarrantsOrRightsUponAdditionalFinancing" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfServiceContractsUnderServiceObligation" id="omex_NumberOfServiceContractsUnderServiceObligation" type="xbrli:integerItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfSharesRedeemed" id="omex_NumberOfSharesRedeemed" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfStockIncentivePlans" id="omex_NumberOfStockIncentivePlans" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsExpirationYearEndMember" id="omex_OperatingLossCarryforwardsExpirationYearEndMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsExpirationYearStartMember" id="omex_OperatingLossCarryforwardsExpirationYearStartMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsExpiringTwoThousandAndEighteenThroughTwoThousandAndTwentyTwoMember" id="omex_OperatingLossCarryforwardsExpiringTwoThousandAndEighteenThroughTwoThousandAndTwentyTwoMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsExpiringTwoThousandAndTwentyEightThroughTwoThousandAndThirtyTwoMember" id="omex_OperatingLossCarryforwardsExpiringTwoThousandAndTwentyEightThroughTwoThousandAndThirtyTwoMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsExpiringTwoThousandAndTwentyThreeThroughTwoThousandAndTwentySevenMember" id="omex_OperatingLossCarryforwardsExpiringTwoThousandAndTwentyThreeThroughTwoThousandAndTwentySevenMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsUtilizedAmount" id="omex_OperatingLossCarryforwardsUtilizedAmount" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperationsAndResearch" id="omex_OperationsAndResearch" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OptionToPurchaseCommonSharesOutstanding" id="omex_OptionToPurchaseCommonSharesOutstanding" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OutOfMoneyPotentialCommonSharesMember" id="omex_OutOfMoneyPotentialCommonSharesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OutstandingPrincipalAmountMortgageLoan" id="omex_OutstandingPrincipalAmountMortgageLoan" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ParticipationRevenueRightsFirstPaymentMember" id="omex_ParticipationRevenueRightsFirstPaymentMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ParticipationRevenueRightsSecondPaymentMember" id="omex_ParticipationRevenueRightsSecondPaymentMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ParticipationRevenueRightsThirdPaymentMember" id="omex_ParticipationRevenueRightsThirdPaymentMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfAccelerationPaymentOfRemainingFaceValue" id="omex_PercentageOfAccelerationPaymentOfRemainingFaceValue" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfAdditionalNetRevenueOwedToCertificateHolders" id="omex_PercentageOfAdditionalNetRevenueOwedToCertificateHolders" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfAdjustedConversionPriceOfQuotedMarketPrices" id="omex_PercentageOfAdjustedConversionPriceOfQuotedMarketPrices" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfCarryingValueOfAdditionalNoteToDetermineChangeInFairValueOfEmbeddedConversionOption" id="omex_PercentageOfCarryingValueOfAdditionalNoteToDetermineChangeInFairValueOfEmbeddedConversionOption" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfConversionPriceEqualToVolumeWeightedAveragePrice" id="omex_PercentageOfConversionPriceEqualToVolumeWeightedAveragePrice" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfDebtInstrumentConversionPriceOnMarketPriceOfCommonStock" id="omex_PercentageOfDebtInstrumentConversionPriceOnMarketPriceOfCommonStock" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfRevenueOwedToCertificateHolders" id="omex_PercentageOfRevenueOwedToCertificateHolders" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfRevenueOwedToCertificateHoldersPerUnit" id="omex_PercentageOfRevenueOwedToCertificateHoldersPerUnit" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfVariableInterest" id="omex_PercentageOfVariableInterest" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForAnniversaryOfInitialClosingDate" id="omex_PeriodForAnniversaryOfInitialClosingDate" type="us-types:durationStringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForRegistrationStatementOfInitialClosingDate" id="omex_PeriodForRegistrationStatementOfInitialClosingDate" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForRegistrationStatementSubjectToReview" id="omex_PeriodForRegistrationStatementSubjectToReview" type="us-types:durationStringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForRegistrationStatementToBeDeclaredEffective" id="omex_PeriodForRegistrationStatementToBeDeclaredEffective" type="us-types:durationStringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForWarrantTerm" id="omex_PeriodForWarrantTerm" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PreferredShareOfSeriesGConvertible" id="omex_PreferredShareOfSeriesGConvertible" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PriorPeriodAccruedCompensationPaidByEquityInstruments" id="omex_PriorPeriodAccruedCompensationPaidByEquityInstruments" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ProceedsFromSaleOfSubsidiaryStock" id="omex_ProceedsFromSaleOfSubsidiaryStock" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ProjectFinancing" id="omex_ProjectFinancing" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ProjectTermLoanMember" id="omex_ProjectTermLoanMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RedeemablePreferredStockDividendPercent" id="omex_RedeemablePreferredStockDividendPercent" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RedeemablePreferredStockTextBlock" id="omex_RedeemablePreferredStockTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RedemptionPriceIncrementPercentage" id="omex_RedemptionPriceIncrementPercentage" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RedemptionPricePercentOfLiquidationValue" id="omex_RedemptionPricePercentOfLiquidationValue" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RedemptionsOfSeniorConvertibleNotes" id="omex_RedemptionsOfSeniorConvertibleNotes" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RemainingAmountOfAccountReceivable" id="omex_RemainingAmountOfAccountReceivable" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RemainingFuturePayments" id="omex_RemainingFuturePayments" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RepaymentOfMortgageAndLoansPayable" id="omex_RepaymentOfMortgageAndLoansPayable" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RepublicProjectMember" id="omex_RepublicProjectMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RestrictedCashAndCashEquivalentsMaturityPeriod" id="omex_RestrictedCashAndCashEquivalentsMaturityPeriod" type="xbrli:gYearMonthItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RestrictedCashAndCashEquivalentsReplenishRequired" id="omex_RestrictedCashAndCashEquivalentsReplenishRequired" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RevenueOwedToCertificateHolders" id="omex_RevenueOwedToCertificateHolders" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RevenueParticipationAgreementValue" id="omex_RevenueParticipationAgreementValue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RevenueParticipationCertificatesPerUnitValue" id="omex_RevenueParticipationCertificatesPerUnitValue" type="us-types:perUnitItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RevenueParticipationRightsTextBlock" id="omex_RevenueParticipationRightsTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RiskFreeRatesUsingZeroCouponCountryTreasurySecurityRangeOfRates" id="omex_RiskFreeRatesUsingZeroCouponCountryTreasurySecurityRangeOfRates" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfAllocationOfCashProceedsRelatedToAdditionalFinancingTableTextBlock" id="omex_ScheduleOfAllocationOfCashProceedsRelatedToAdditionalFinancingTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfAllocationOfCashProceedsToDerivativeComponentsAtTheirFairValuesTableTextBlock" id="omex_ScheduleOfAllocationOfCashProceedsToDerivativeComponentsAtTheirFairValuesTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfComponentsOfDerivativeLiabilitiesTableTextBlock" id="omex_ScheduleOfComponentsOfDerivativeLiabilitiesTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfConcentrationOfCreditRiskTable" id="omex_ScheduleOfConcentrationOfCreditRiskTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem"/>
  <element name="ScheduleOfInventoryTableTextBlock" id="omex_ScheduleOfInventoryTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfRevenueParticipationRightsTableTextBlock" id="omex_ScheduleOfRevenueParticipationRightsTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsTableTextBlock" id="omex_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SecuredCollateral" id="omex_SecuredCollateral" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeniorConvertibleDebitInterestSettledWithCommonStockIssuance" id="omex_SeniorConvertibleDebitInterestSettledWithCommonStockIssuance" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeniorConvertibleNoteMember" id="omex_SeniorConvertibleNoteMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeniorConvertibleNotesMember" id="omex_SeniorConvertibleNotesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeriesGPreferredStockConversion" id="omex_SeriesGPreferredStockConversion" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SettlementOfVendorPayableWithSubsidiaryStock" id="omex_SettlementOfVendorPayableWithSubsidiaryStock" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceCondition" id="omex_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceCondition" type="xbrli:stringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ShareBasedCompensationAwardsOptionsEstimatedWeightedAverageGrantDateFairValue" id="omex_ShareBasedCompensationAwardsOptionsEstimatedWeightedAverageGrantDateFairValue" type="num:perShareItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesOfCommonStockIssuableUponExerciseOfWarrant" id="omex_SharesOfCommonStockIssuableUponExerciseOfWarrant" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesReceivedFromExchange" id="omex_SharesReceivedFromExchange" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesReceivedFromUnconsolidatedEntities" id="omex_SharesReceivedFromUnconsolidatedEntities" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesUsedInComputationForEarningPerShareBasic" id="omex_SharesUsedInComputationForEarningPerShareBasic" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ShortTermInvestmentsMaturityPeriod" id="omex_ShortTermInvestmentsMaturityPeriod" type="xbrli:stringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SilverQuantity" id="omex_SilverQuantity" type="num:weightItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SmmProjectLimitedLiabilityCompanyMember" id="omex_SmmProjectLimitedLiabilityCompanyMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SsGairsoppaMember" id="omex_SsGairsoppaMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockholdersDeficitTextualAbstract" id="omex_StockholdersDeficitTextualAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockIssuedDuringPeriodSaleOfSubsidiaryStockPerSharePrice" id="omex_StockIssuedDuringPeriodSaleOfSubsidiaryStockPerSharePrice" type="num:perShareItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockIssuedDuringPeriodSharesSaleOfSubsidiaryStock" id="omex_StockIssuedDuringPeriodSharesSaleOfSubsidiaryStock" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockIssuedDuringPeriodValueSaleOfSubsidiaryStock" id="omex_StockIssuedDuringPeriodValueSaleOfSubsidiaryStock" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceEightMember" id="omex_StockOptionsExercisePriceEightMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceElevenMember" id="omex_StockOptionsExercisePriceElevenMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceFiveMember" id="omex_StockOptionsExercisePriceFiveMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceFourMember" id="omex_StockOptionsExercisePriceFourMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceNineMember" id="omex_StockOptionsExercisePriceNineMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceSevenMember" id="omex_StockOptionsExercisePriceSevenMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceSixMember" id="omex_StockOptionsExercisePriceSixMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceTenMember" id="omex_StockOptionsExercisePriceTenMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceThreeMember" id="omex_StockOptionsExercisePriceThreeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsExercisePriceTwoMember" id="omex_StockOptionsExercisePriceTwoMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TaxBenefitsAndLiabilitiesPriorToAnyValuationAllowancesRelatedToStockOptionPlans" id="omex_TaxBenefitsAndLiabilitiesPriorToAnyValuationAllowancesRelatedToStockOptionPlans" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TemporaryEquityConversionRightRatio" id="omex_TemporaryEquityConversionRightRatio" type="num:perShareItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TemporaryEquityLiquidationPreferenceValue" id="omex_TemporaryEquityLiquidationPreferenceValue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TemporaryEquityPaidInCapital" id="omex_TemporaryEquityPaidInCapital" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TemporaryEquityValueExchange" id="omex_TemporaryEquityValueExchange" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TemporaryEquityValueFinancing" id="omex_TemporaryEquityValueFinancing" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TermLoanAmendmentMember" id="omex_TermLoanAmendmentMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TermLoanMember" id="omex_TermLoanMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ThirdPartyMember" id="omex_ThirdPartyMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantDerivativeMember" id="omex_WarrantDerivativeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantsAndOptionsMember" id="omex_WarrantsAndOptionsMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantsExercisePriceFiveMember" id="omex_WarrantsExercisePriceFiveMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantsExercisePriceFourMember" id="omex_WarrantsExercisePriceFourMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantyExpiryPeriod" id="omex_WarrantyExpiryPeriod" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WeightedAverageNumberOfSharesAdjustmentBasic" id="omex_WeightedAverageNumberOfSharesAdjustmentBasic" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WeightOfSilverBullionRecovered" id="omex_WeightOfSilverBullionRecovered" type="num:massItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WeightOfSilverForWhichContractEnteredToMitigateRisk" id="omex_WeightOfSilverForWhichContractEnteredToMitigateRisk" type="num:massItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
</schema>
