<SEC-DOCUMENT>0001567619-18-001581.txt : 20180821
<SEC-HEADER>0001567619-18-001581.hdr.sgml : 20180821
<ACCEPTANCE-DATETIME>20180821180713
ACCESSION NUMBER:		0001567619-18-001581
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180818
FILED AS OF DATE:		20180821
DATE AS OF CHANGE:		20180821

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Demarest Craig
		CENTRAL INDEX KEY:			0001436705

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-06311
		FILM NUMBER:		181031105

	MAIL ADDRESS:	
		STREET 1:		C/O TIDEWATER, INC
		STREET 2:		601 POYDRAS STREET, SUITE 1900
		CITY:			NEW ORLEANS
		STATE:			LA
		ZIP:			70130

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TIDEWATER INC
		CENTRAL INDEX KEY:			0000098222
		STANDARD INDUSTRIAL CLASSIFICATION:	WATER TRANSPORTATION [4400]
		IRS NUMBER:				720487776
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		6002 ROGERDALE ROAD
		STREET 2:		SUITE 600
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77072
		BUSINESS PHONE:		7134705300

	MAIL ADDRESS:	
		STREET 1:		6002 ROGERDALE ROAD
		STREET 2:		SUITE 600
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77072

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	TIDEWATER MARINE SERVICE INC
		DATE OF NAME CHANGE:	19780724
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-08-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000098222</issuerCik>
        <issuerName>TIDEWATER INC</issuerName>
        <issuerTradingSymbol>TDW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001436705</rptOwnerCik>
            <rptOwnerName>Demarest Craig</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TIDEWATER INC.</rptOwnerStreet1>
            <rptOwnerStreet2>6002 ROGERDALE ROAD, SUITE 600</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77072</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Principal Accounting Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-08-18</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2668</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>30.23</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20459</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-08-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4955</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>31.115</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15504</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by 401(k) Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The transaction reported on this Form 4 was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person.</footnote>
        <footnote id="F2">This transaction was executed in multiple trades at prices ranging from $30.76 to $31.48.  The price reported above reflects the weighted average sale price.  Upon request from the SEC staff, the issuer, or a security holder of the issuer, the Reporting Person hereby undertakes to provide the requesting party with full information regarding the number of shares and prices at which the transaction was effected.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Bruce D. Lundstrom as Agent and Attorney-in-Fact for Craig J. Demarest</signatureName>
        <signatureDate>2018-08-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
