-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 6m76IOm7swFLrM3s/vVO8A==

<SEC-DOCUMENT>0000919574-09-014435.txt : 20090813
<SEC-HEADER>0000919574-09-014435.hdr.sgml : 20090813
<ACCEPTANCE-DATETIME>20090812184730
ACCESSION NUMBER:		0000919574-09-014435
CONFORMED SUBMISSION TYPE:	D/A
PUBLIC DOCUMENT COUNT:		1
ITEM INFORMATION:		Rule 506
ITEM INFORMATION:		Investment Company Act Section 3(c)
ITEM INFORMATION:		Section 3(c)(7)
FILED AS OF DATE:		20090813
DATE AS OF CHANGE:		20090812
EFFECTIVENESS DATE:		20090813

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Pequot Mariner Offshore Institutional fund LTD
		CENTRAL INDEX KEY:			0001378697
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			E9
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		D/A
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	021-95734
		FILM NUMBER:		091008134

	BUSINESS ADDRESS:	
		STREET 1:		C/O PEQUOT CAPITAL MANAGEMENT, INC.
		STREET 2:		500 NYALA FARM ROAD
		CITY:			WESTPORT
		STATE:			CT
		ZIP:			06880
		BUSINESS PHONE:		441-295-9166

	MAIL ADDRESS:	
		STREET 1:		HEMISPHERE HOUSE 9 CHURCH ST
		STREET 2:		P O BOX HM 951
		CITY:			HAMILTON HM DX BERMUDA
		STATE:			D0
		ZIP:			HM DX
</SEC-HEADER>
<DOCUMENT>
<TYPE>D/A
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<edgarSubmission>

    <schemaVersion>X0502</schemaVersion>

    <submissionType>D/A</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001378697</cik>
        <entityName>Pequot Mariner Offshore Institutional fund LTD</entityName>
        <issuerAddress>
            <street1>c/o Walker SPV Limited</street1>
            <street2>Walker House, Box 908 GT, Mary Street</street2>
            <city>Grand Cayman</city>
            <stateOrCountry>E9</stateOrCountry>
            <zipCode>KY1-9001</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>441-295-9166</issuerPhoneNumber>
        <issuerPreviousNameList>
            <previousName>Pequot Mariner Offshore Institutional Fund, Ltd.</previousName>
        </issuerPreviousNameList>
        <jurisdictionOfInc>CAYMAN ISLANDS</jurisdictionOfInc>
        <entityType>Other</entityType>
        <entityTypeOtherDesc>Cayman Islands Exempted Company</entityTypeOtherDesc>
        <yearOfInc>
            <withinFiveYears>true</withinFiveYears>
            <value>2005</value>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Thomas</firstName>
                <middleName></middleName>
                <lastName>Scalia</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Manatuck Hill Partners, LLC</street1>
                <street2>1465 Post Road East</street2>
                <city>Westport</city>
                <stateOrCountry>CT</stateOrCountry>
                <zipCode>06880</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Alan</firstName>
                <middleName></middleName>
                <lastName>Tooker</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o A.R.C. Directors Ltd</street1>
                <street2>Grand Pavilion Commercial Centre Suite 7</street2>
                <city>Grand Cayman</city>
                <stateOrCountry>E9</stateOrCountry>
                <zipCode>KY1-1003</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Ramona</firstName>
                <middleName></middleName>
                <lastName>Bowry</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o A.R.C. Directors Ltd</street1>
                <street2>Grand Pavilion Commercial Centre Suite 7</street2>
                <city>Grand Cayman</city>
                <stateOrCountry>E9</stateOrCountry>
                <zipCode>KY1-1104</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Mark</firstName>
                <middleName>A.</middleName>
                <lastName>Broach</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Manatuck Hill Partners, LLC</street1>
                <street2>1465 Post Road East</street2>
                <city>Wesport</city>
                <stateOrCountry>CT</stateOrCountry>
                <zipCode>06880</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Pooled Investment Fund</industryGroupType>
            <investmentFundInfo>
                <investmentFundType>Hedge Fund</investmentFundType>
                <is40Act>false</is40Act>
            </investmentFundInfo>
        </industryGroup>
        <issuerSize>
            <aggregateNetAssetValueRange>Decline to Disclose</aggregateNetAssetValueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
            <item>3C</item>
            <item>3C.7</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>true</isAmendment>
                <previousAccessionNumber>0001404962-09-000013</previousAccessionNumber>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2006-10-01</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isPooledInvestmentFundType>true</isPooledInvestmentFundType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>5000000</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>Indefinite</totalOfferingAmount>
            <totalAmountSold>11755434</totalAmountSold>
            <totalRemaining>Indefinite</totalRemaining>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>8</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
                <isEstimate>true</isEstimate>
            </grossProceedsUsed>
            <clarificationOfResponse>The Investment Manager (or its affiliate) is entitled to receive an annual management fee in an amount equal to a specified percentage of assets under management.</clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>Manatuck Hill Mariner Offshore Institutional Fund, Ltd.</issuerName>
                <signatureName>/s/ Thomas Scalia</signatureName>
                <nameOfSigner>Thomas Scalia</nameOfSigner>
                <signatureTitle>Authorized Person</signatureTitle>
                <signatureDate>2009-07-30</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----