<SEC-DOCUMENT>0001179110-18-009334.txt : 20180703
<SEC-HEADER>0001179110-18-009334.hdr.sgml : 20180703
<ACCEPTANCE-DATETIME>20180703162123
ACCESSION NUMBER:		0001179110-18-009334
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180626
FILED AS OF DATE:		20180703
DATE AS OF CHANGE:		20180703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Perestroika (Cyprus) Ltd
		CENTRAL INDEX KEY:			0001737912
		STATE OF INCORPORATION:			G4
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38373
		FILM NUMBER:		18937599

	BUSINESS ADDRESS:	
		STREET 1:		TRANSOCEAN
		STREET 2:		TURMSTRASSE 30
		CITY:			STEINHAUSEN
		STATE:			V8
		ZIP:			6312
		BUSINESS PHONE:		7132327654

	MAIL ADDRESS:	
		STREET 1:		TRANSOCEAN
		STREET 2:		TURMSTRASSE 30
		CITY:			STEINHAUSEN
		STATE:			V8
		ZIP:			6312

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Transocean Ltd.
		CENTRAL INDEX KEY:			0001451505
		STANDARD INDUSTRIAL CLASSIFICATION:	DRILLING OIL & GAS WELLS [1381]
		IRS NUMBER:				980599916
		STATE OF INCORPORATION:			V8
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		TURMSTRASSE 30
		CITY:			STEINHAUSEN
		STATE:			V8
		ZIP:			6312
		BUSINESS PHONE:		41 41 749 0500

	MAIL ADDRESS:	
		STREET 1:		TURMSTRASSE 30
		CITY:			STEINHAUSEN
		STATE:			V8
		ZIP:			6312
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-06-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001451505</issuerCik>
        <issuerName>Transocean Ltd.</issuerName>
        <issuerTradingSymbol>RIG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001737912</rptOwnerCik>
            <rptOwnerName>Perestroika (Cyprus) Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PERESTROIKA AS</rptOwnerStreet1>
            <rptOwnerStreet2>TURMSTRASSE 30</rptOwnerStreet2>
            <rptOwnerCity>STEINHAUSEN</rptOwnerCity>
            <rptOwnerState>V8</rptOwnerState>
            <rptOwnerZipCode>6312</rptOwnerZipCode>
            <rptOwnerStateDescription>SWITZERLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2018-06-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value>E</value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>660000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>33096351</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On June 26, 2018, Perestroika AS transferred 660,000 of its Shares of Transocean Ltd. (the &quot;Company&quot;) to Perestroika (Cyprus) Ltd.  Perestroika (Cyprus) Ltd. is a wholly owned subsidiary of Perestroika AS.  Mr. Mohn is the sole owner and director of Perestroika AS and is the beneficial owner of all securities owned by Perestroika AS and Perestroika (Cyprus) Ltd.  While this change in the form of Perestroika AS's and Mr. Mohn's beneficial ownership is exempt from reporting, this Form 4 is being voluntarily filed to report this change.</footnote>
    </footnotes>

    <remarks>Perestroika (Cyprus) Ltd. is a wholly owned subsidiary of Perestroika AS. Due to Perestroika AS's designation of a member of the board of directors of the Company, Perestroika (Cyprus) Ltd. may be deemed to be a director of the Company by deputization. Perestroika AS's right to designate a member of the Company's board of directors has since terminated.</remarks>

    <ownerSignature>
        <signatureName>/s/ Daniel Ro-Trock, by Power of Attorney</signatureName>
        <signatureDate>2018-07-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
