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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-03-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001325159</issuerCik>
        <issuerName>FreeSeas Inc.</issuerName>
        <issuerTradingSymbol>FREE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001166432</rptOwnerCik>
            <rptOwnerName>SONKIN PAUL D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>460 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>see footnote #1</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001101758</rptOwnerCik>
            <rptOwnerName>HUMMINGBIRD VALUE FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>460 PARK AVENUE, 12TH FL</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>see footnote #1</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001243818</rptOwnerCik>
            <rptOwnerName>HUMMINGBIRD MICROCAP VALUE FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>460 PARK AVENUE, 12TH FL</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>see footnote #1</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001276582</rptOwnerCik>
            <rptOwnerName>HUMMINGBIRD CONCENTRATED FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>460 PARK AVENUE, 12TH FL</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>see footnote #1</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001164073</rptOwnerCik>
            <rptOwnerName>HUMMINGBIRD MANAGEMENT LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>460 PARK AVENUE, 12TH FL</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>see footnote #1</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001249876</rptOwnerCik>
            <rptOwnerName>HUMMINGBIRD CAPITAL LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>460 PARK AVENUE, 12TH FL</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>see footnote #1</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2006-03-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5100</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.625</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>147100</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 4 is filed jointly by Paul D. Sonkin, The Hummingbird Value Fund, L.P. (&quot;HVF&quot;), The Hummingbird Microcap Value Fund, L.P.(&quot;Microcap&quot;),The Hummingbird Concentrated Fund, L.P. (&quot;Concentrated&quot;), Hummingbird Capital, LLC, and Hummingbird Management, LLC. Paul D. Sonkin is the Managing Member of (a) Hummingbird Capital, LLC, the general partner of HVF, Microcap, and Concentrated, and (b) Hummingbird Management, LLC, the investment manager to HVF, Microcap, and Concentrated. Accordingly, each of Paul D. Sonkin, Hummingbird Capital, LLC, and Hummingbird Management, LLC may be deemed to beneficially own the securities owned by HVF, Microcap, and Concentrated, reported herein. The Reporting Persons are members of a Section 13(d) group that owns more than 10% of the Issuer's outstanding Common Stock.</footnote>
        <footnote id="F2">Acquired by The Hummingbird Concentrated Fund, LP.</footnote>
        <footnote id="F3">Owned directly by The Hummingbird Concentrated Fund, L.P., and indirectly by Paul D. Sonkin, Hummingbird Capital, LLC,  and Hummingbird Management, LLC, each of which disclaims beneficial ownership of the securities owned by The Hummingbird Concentrated Fund, L.P., except to the extent that each such party has an interest, if any, in The Hummingbird Concentrated Fund, L.P.

In addition, HVF owns 335,693 shares and warrants directly, and Microcap owns 335,589 shares and warrants directly. These shares and warrants are owned indirectly by Paul D. Sonkin, Hummingbird Capital, LLC,  and Hummingbird Management, LLC, each of which disclaims beneficial ownership of the securities owned by HVF and Microcap., except to the extent that each such party has an interest, if any, in HVF and Microcap.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Paul D. Sonkin</signatureName>
        <signatureDate>2006-03-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>The Hummingbird Value Fund, LP</signatureName>
        <signatureDate>2006-03-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>The Hummingbird Microcap Value Fund, LP</signatureName>
        <signatureDate>2006-03-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>The Hummingbird Concentrated Fund, LP</signatureName>
        <signatureDate>2006-03-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Hummingbird Management, LLC</signatureName>
        <signatureDate>2006-03-24</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Hummingbird Capital, LLC</signatureName>
        <signatureDate>2006-03-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
