<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-11-27</periodOfReport>

    <notSubjectToSection16>true</notSubjectToSection16>

    <issuer>
        <issuerCik>0001038914</issuerCik>
        <issuerName>GLOBALSANTAFE CORP</issuerName>
        <issuerTradingSymbol>GSF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001180364</rptOwnerCik>
            <rptOwnerName>MCCULLOCH JAMES L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>15375 MEMORIAL DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77079</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>Sr VP &amp; Gen Counsel</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Ordinary Shares, $0.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2007-11-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>31800</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Ordinary Shares, $0.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2007-11-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>13466</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>24.73</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-11-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>21450</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-11-27</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-01-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, $0.01 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21450</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>37.48</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-11-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>16170</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-11-27</value>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-02-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, $0.01 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>16170</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Appreciation Right</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>49.5</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-11-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>45500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F7"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-11-27</value>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-01-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, $0.01 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>45500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Appreciation Right</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>61.24</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-11-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>40000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F9"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2007-11-27</value>
                <footnoteId id="F10"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-12-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, $0.01 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>40000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to the terms of the Agreement and Plan of Merger dated as of July 21, 2007 (the &quot;Merger Agreement&quot;) among Transocean Inc. (&quot;Transocean&quot;), GlobalSantaFe Corporation (&quot;GlobalSantaFe&quot;), and Transocean Worldwide Inc., at the effective time of the merger, each outstanding ordinary share of GlobalSantaFe, par value $0.01 per share (&quot;GlobalSantaFe Ordinary Shares&quot;) was converted into the right to receive .4757 ordinary shares of Transocean, par value $0.01 per share (&quot;Transocean Ordinary Shares&quot;), having a market value of $129.39 per share Transocean Ordinary Share as of the close of trading on the trading day immediately preceding the effective date of the reclassification of Transocean's ordinary shares and the merger, and $22.46 in cash.</footnote>
        <footnote id="F2">Pursuant to the terms of the Agreement and Plan of Merger dated as of July 21, 2007 (the &quot;Merger Agreement&quot;) among Transocean Inc. (&quot;Transocean&quot;), GlobalSantaFe Corporation (&quot;GlobalSantaFe&quot;), and Transocean Worldwide Inc., at the effective time of the merger, each outstanding ordinary share of GlobalSantaFe, par value $0.01 per share (&quot;GlobalSantaFe Ordinary Shares&quot;) was converted into the right to receive .4757 ordinary shares of Transocean, par value $0.01 per share (&quot;Transocean Ordinary Shares&quot;), having a market value of $129.39 per share Transocean Ordinary Share as of the close of trading on the trading day immediately preceding the effective date of the reclassification of Transocean's ordinary shares and the merger, and $22.46 in cash.</footnote>
        <footnote id="F3">Pursuant to the Merger Agreement, at the effective time of the merger, each outstanding option to purchase GlobalSantaFe Ordinary Shares (&quot;GlobalSantaFe Option&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe Option was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe Option immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
        <footnote id="F4">Pursuant to the Merger Agreement, at the effective time of the merger, each outstanding option to purchase GlobalSantaFe Ordinary Shares (&quot;GlobalSantaFe Option&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe Option was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe Option immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
        <footnote id="F5">Pursuant to the Merger Agreement, at the effective time of the merger, each outstanding option to purchase GlobalSantaFe Ordinary Shares (&quot;GlobalSantaFe Option&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe Option was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe Option immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
        <footnote id="F6">Pursuant to the Merger Agreement, at the effective time of the merger, each outstanding option to purchase GlobalSantaFe Ordinary Shares (&quot;GlobalSantaFe Option&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe Option was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe Option immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
        <footnote id="F7">Pursuant to the Merger Agreement, at the effective time of the Merger, each outstanding GlobalSantaFe stock-settled stock appreciation right (&quot;GlobalSantaFe SAR&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe SAR was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe SAR immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
        <footnote id="F8">Pursuant to the Merger Agreement, at the effective time of the Merger, each outstanding GlobalSantaFe stock-settled stock appreciation right (&quot;GlobalSantaFe SAR&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe SAR was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe SAR immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
        <footnote id="F9">Pursuant to the Merger Agreement, at the effective time of the Merger, each outstanding GlobalSantaFe stock-settled stock appreciation right (&quot;GlobalSantaFe SAR&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe SAR was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe SAR immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
        <footnote id="F10">Pursuant to the Merger Agreement, at the effective time of the Merger, each outstanding GlobalSantaFe stock-settled stock appreciation right (&quot;GlobalSantaFe SAR&quot;) was assumed by Transocean and became fully vested and exercisable for a number of Transocean Ordinary Shares equal to the number of GlobalSantaFe Ordinary Shares for which such GlobalSantaFe SAR was exercisable immediately prior to the merger multiplied by 0.6368 (rounded down to the nearest whole share) with a per share exercise price equal to the exercise price of the GlobalSantaFe SAR immediately prior to the merger divided by 0.6368 (rounded up to the nearest whole cent).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>A Krezel, Atty-in-fact</signatureName>
        <signatureDate>2007-11-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
