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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2018-03-13</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001332639</issuerCik>
        <issuerName>Seaspan CORP</issuerName>
        <issuerTradingSymbol>SSW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001548624</rptOwnerCik>
            <rptOwnerName>Carlyle Group Management L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W. SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001527166</rptOwnerCik>
            <rptOwnerName>Carlyle Group L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001548629</rptOwnerCik>
            <rptOwnerName>Carlyle Holdings II GP L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001548630</rptOwnerCik>
            <rptOwnerName>Carlyle Holdings II L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001548632</rptOwnerCik>
            <rptOwnerName>Carlyle Holdings III GP Management L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001548631</rptOwnerCik>
            <rptOwnerName>Carlyle Holdings III GP L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001548633</rptOwnerCik>
            <rptOwnerName>Carlyle Holdings III GP Sub L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001548634</rptOwnerCik>
            <rptOwnerName>Carlyle Holdings III L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE CARLYLE GROUP, 1001</rptOwnerStreet1>
            <rptOwnerStreet2>PENNSYLVANIA AVE., N.W., SUITE 220 SOUTH</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20004-2505</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Series D Preferred Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1869200</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes: (i) 47,028 shares of Series D Preferred Shares held by CP V Coinvestment A Cayman, L.P.; (ii) 9,628 shares of Series D Preferred Shares held by CP V Coinvestment B Cayman, L.P.; (iii) 17,423 shares of Series D Preferred Shares held by CAP III Co-Investment, L.P.; (iv) 1,363,936 shares of Series D Preferred Shares held by Carlyle Partners V Cayman TE, L.P.; (v) 356,417 shares of Series D Preferred Shares held by CAP III Maritime AIV, L.P.; and (vi) 74,768 shares of Series D Preferred Shares held by Carlyle-Eight Finance Asia Co-Investment Partners, L.P.</footnote>
        <footnote id="F2">Carlyle Group Management L.L.C. is the general partner of The Carlyle Group L.P., which is a publicly traded entity listed on NASDAQ. The Carlyle Group L.P. is the managing member of each of Carlyle Holdings II GP L.L.C. and Carlyle Holdings III GP Management L.L.C.</footnote>
        <footnote id="F3">Carlyle Holdings II GP L.L.C. is the general partner of Carlyle Holdings II L.P., which is the general partner of TC Group Cayman Investment Holdings, L.P., which is the general partner of TC Group Cayman Investment Holdings Sub L.P., which is the sole member of each of CP V General Partner, L.L.C. and CAP III, L.L.C. CP V General Partner, L.L.C. is the general partner of TC Group V Cayman, L.P., which is the general partner of each of CP V Coinvestment A Cayman, L.P. and CP V Coinvestment B Cayman, L.P. CAP III, L.L.C. is the general partner of CAP III General Partner, L.P., which is the general partner of CAP III Co-Investment, L.P.</footnote>
        <footnote id="F4">Carlyle Holdings III GP Management L.L.C. is the general partner of Carlyle Holdings III GP L.P., which is the sole member of Carlyle Holdings III GP Sub L.L.C., which is the general partner of Carlyle Holdings III L.P., which is the general partner of TC Group Cayman L.P., which is the general partner of TC Group Cayman Sub, L.P., which is the sole shareholder of each of CP V S3 GP, Ltd. and CAP III S3 Ltd. CP V S3 GP, Ltd. is the general partner of TC Group V Cayman S3, L.P., which is the general partner of Carlyle Partners V Cayman TE, L.P. CAP III S3 Ltd. is the general partner of CAP III General Partner S3, L.P., which is the general partner of each of CAP III Maritime AIV, L.P. and Carlyle-Eight Finance Asia Co-Investment Partners, L.P.</footnote>
    </footnotes>

    <remarks>Due to the limitations of the electronic filing system TC Group Cayman Investment Holdings, L.P., TC Group Cayman Investment Holdings Sub L.P., CP V General Partner, L.L.C., TC Group V Cayman, L.P., CP V Coinvestment A Cayman, L.P., CP V Coinvestment B Cayman, L.P., CAP III, L.L.C., CAP III General Partner, L.P., CAP III Co-Investment, L.P., TC Group Cayman L.P., TC Group Cayman Sub, L.P., CP V S3 GP, Ltd., TC Group V Cayman S3, L.P., Carlyle Partners V Cayman TE, L.P., CAP III S3 Ltd., CAP III General Partner S3, L.P., CAP III Maritime AIV, L.P., and Carlyle-Eight Finance Asia Co-Investment Partners, L.P. are filing a separate Form 3.</remarks>

    <ownerSignature>
        <signatureName>Carlyle Group Management L.L.C., By: /s/ William E. Conway, Jr., Name: William E. Conway, Jr., Title: Co-Executive Chairman &amp; Co-Chief Investment Officer</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>The Carlyle Group L.P., By: Carlyle Group Management L.L.C., its general partner, By: /s/ William E. Conway, Jr., Name:	William E. Conway, Jr., Title: Co-Executive Chairman &amp; Co-Chief Investment Officer</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Carlyle Holdings II GP L.L.C., By: The Carlyle Group L.P., its managing member, By: Carlyle Group Management L.L.C., its general partner, By: /s/ William E. Conway, Jr., Name: William E. Conway, Jr., Title: 	Co-Executive Chairman &amp; Co-Chief Investment Off</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Carlyle Holdings II L.P., By: /s/ William E. Conway, Jr., Name:	William E. Conway, Jr., Title: Co-Executive Chairman &amp; Co-Chief Investment Officer</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Carlyle Holdings III GP Management L.L.C., By: The Carlyle Group L.P., its sole manager, By: Carlyle Group Management L.L.C., its general partner, By: /s/ William E. Conway, Jr., Name: William E. Conway, Jr., Title: Co-Exec Chairman &amp; Co-CIO</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Carlyle Holdings III GP L.P., By: Carlyle Holdings III GP Management L.L.C., its general partner, By: The Carlyle Group L.P., its sole manager, By: Carlyle Group Management L.L.C., its general partner, By: /s/ William E. Conway, Jr.</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Carlyle Holdings III GP Sub L.L.C., By: Carlyle Holdings III GP L.P., By: Carlyle Holdings III GP Management L.L.C., By: The Carlyle Group L.P., By: Carlyle Group Management L.L.C., By: /s/ William E. Conway, Jr.</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Carlyle Holdings III L.P., By: /s/ William E. Conway, Jr., Name: William E. Conway, Jr., Title: Co-Executive Chairman &amp; Co-Chief Investment Officer</signatureName>
        <signatureDate>2018-04-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
