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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-08-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000351834</issuerCik>
        <issuerName>SunOpta Inc.</issuerName>
        <issuerTradingSymbol>STKL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001687181</rptOwnerCik>
            <rptOwnerName>Oaktree Huntington Investment Fund II, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001687608</rptOwnerCik>
            <rptOwnerName>Oaktree Huntington Investment Fund II GP, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001499005</rptOwnerCik>
            <rptOwnerName>Oaktree Fund GP, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001402746</rptOwnerCik>
            <rptOwnerName>OAKTREE FUND GP I, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001403530</rptOwnerCik>
            <rptOwnerName>Oaktree Capital I, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001407178</rptOwnerCik>
            <rptOwnerName>OCM HOLDINGS I, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001407181</rptOwnerCik>
            <rptOwnerName>OAKTREE HOLDINGS, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001403528</rptOwnerCik>
            <rptOwnerName>Oaktree Capital Group, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001403525</rptOwnerCik>
            <rptOwnerName>Oaktree Capital Group Holdings GP, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001001085</rptOwnerCik>
            <rptOwnerName>BROOKFIELD ASSET MANAGEMENT INC.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O OAKTREE CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>333 SOUTH GRAND AVENUE, 28TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Cash-Settled Total Return Swap</value>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>6.05</value>
                <footnoteId id="F7"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-08-18</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>1</equitySwapInvolved>
                <footnoteId id="F4"/>
                <footnoteId id="F5"/>
                <footnoteId id="F6"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2020-08-18</value>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-08-18</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>544981</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the derivative security (but not the underlying security referenced thereby) owned directly by Oaktree Huntington Investment Fund II, L.P. (&quot;OHIF&quot;). This Form 4 is also being filed by (i) Oaktree Huntington Investment Fund II GP, L.P. (&quot;OHIF GP&quot;) in its capacity as general partner of OHIF GP; (ii) Oaktree Fund GP, LLC (&quot;Fund GP&quot;) in its capacity as general partner of OHIF GP; (iii) Oaktree Fund GP I, L.P. (&quot;GP I&quot;) in its capacity as managing member of Fund GP; (iv) Oaktree Capital I, L.P. (&quot;Capital I&quot;) in its capacity as the general partner of GP I; (v) OCM Holdings I, LLC (&quot;Holdings I&quot;) in its capacity as the general partner of Capital I; (vi) Oaktree Holdings, LLC (&quot;Holdings LLC&quot;) in its capacity as the managing member of Holdings I;.</footnote>
        <footnote id="F2">(Continued from Footnote 1) (vii) Oaktree Capital Group, LLC (&quot;OCG&quot;) in its capacity as the managing member of Holdings LLC; (viii) Oaktree Capital Group Holdings GP, LLC (&quot;OCGH GP&quot;) in its capacity as the duly appointed manager of OCG; (ix) Brookfield Asset Management, Inc. (&quot;BAM&quot;) in its capacity as the indirect owner of the class A units of OCG; and (x) Partners Limited, in its capacity as the sole owner of Class B Limited Voting Shares of BAM (each a &quot;Reporting Person&quot; and, collectively, the &quot;Reporting Persons&quot;).</footnote>
        <footnote id="F3">Each Reporting Person disclaims beneficial ownership of all equity securities reported herein except to the extent of its respective pecuniary interest therein, and the filing of this Form 4 shall not be construed as an admission that any such Reporting Person is the beneficial owner of any equity securities covered by this Form 4.</footnote>
        <footnote id="F4">OHIF (the &quot;Trading Fund&quot;) has entered into a cash-settled total return swap with respect to the number of common shares of SunOpta Inc. (the &quot;Issuer&quot;) specified herein (the &quot;Cash-Settled Swap&quot;). The Cash-Settled Swap provides the Trading Fund with economic results that are comparable to the economic results of ownership of 544,981 of the Issuer's common shares (the &quot;Subject Shares&quot;). Upon termination of the the Cash-Settled Swap, the Trading Fund will be obligated to pay to the counterparty any negative price performance of the terminated quantity of the Subject Shares, and the counterparty will be obligated to pay the Trading Fund any positive price performance of the specified quantity of the Subject Shares, in each case subject to customary adjustments and limitations.</footnote>
        <footnote id="F5">(Continued from Footnote 4) The Cash-Settled Swap was initially executed at a price of $6.05000. The Cash-Settled Swap is exclusively cash-settled and does not provide the Trading Fund with the direct or indirect power to vote or direct the voting or dispose of or direct the disposition of the Subject Shares. Additionally, the Cash-Settled Swap does not require the counterparty thereto to acquire, hold, vote or dispose of any securities of the Issuer, including without limitation, the Subject Shares. The counterparties to the Cash-Settled Swap are unaffiliated third party financial institutions. The Cash-Settled Swap may generally be terminated by the Trading Funds on any business day, subject to customary adjustments and limitations.</footnote>
        <footnote id="F6">Under the terms of the Cash-Settled Swap, generally, the Trading Fund will be obligated to pay to the counterparty certain fees and commissions and the counterparty will be obligated to pay to the Trading Fund an amount in cash equal to any dividends on the Subject Shares, subject to customary adjustments and limitations.</footnote>
        <footnote id="F7">Reflects the initial price under the Cash-Settled Swap.</footnote>
        <footnote id="F8">See Footnote 4 above discussing the Trading Fund's ability to terminate the Cash-Settled Swap on any business day, subject to customary adjustments and limitations.</footnote>
    </footnotes>

    <remarks>Form 1 of 2.</remarks>

    <ownerSignature>
        <signatureName>OAKTREE HUNTINGTON INVESTMENT FUND II, LP.  By: OAKTREE HUNTINGTON INVESTMENT FUND II GP, L.P. Its: GP, By: OAKTREE FUND GP, LLC, its GP, By: Oaktree Fund GP I, L.P. Its: Managing Member, By: /s/ Ting He, Authorized Signatory</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OAKTREE HUNTINGTON INVESTMENT FUND II GP, L.P. Its: GP, By: OAKTREE FUND GP, LLC, its GP, By: Oaktree Fund GP I, L.P. Its: Managing Member, By: /s/ Ting He, Authorized Signatory</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OAKTREE FUND GP, LLC By: Oaktree Fund GP I, L.P. Its: Managing Member By: /s/ Ting He, Authorized Signatory</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OAKTREE FUND GP I, L.P. By: /s/ Ting He, Authorized Signatory</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OAKTREE CAPITAL I, L.P. By: /s/ Ting He, Vice President</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OCM HOLDINGS I, LLC By: /s/ Ting He, Vice President</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OAKTREE HOLDINGS, LLC By: /s/ Ting He, Vice President</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OAKTREE CAPITAL GROUP, LLC By: Oaktree Capital Group Holdings GP, LLC Its: Manager By: /s/ Ting He, Vice President</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>OAKTREE CAPITAL GROUP HOLDINGS GP, LLC By: /s/ Ting He, Vice President</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>BROOKFIELD ASSET MANAGEMENT INC. By: /s/ Jessica Diab, Vice President, Legal &amp; Regulatory</signatureName>
        <signatureDate>2020-08-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
