Sea　ice　distribution　is　an　important　indicator　of　ice　conditions　and　regional　climate　change　in　the　Bohai　Sea　(China).　In　this　study,　we　monitored　the　spatiotemporal　distribution　of　the　Bohai　Sea　ice　in　the　winter　of　2017-2018　by　developing　sea　ice　information　indexes　using　300　m　resolution　Sentinel-3　Ocean　and　Land　Color　Instrument　(OLCI)　images.　We　assessed　and　validated　the　index　performance　using　Sentinel-2　MultiSpectral　Instrument　(MSI)　images　with　higher　spatial　resolution.　The　results　indicate　that　the　proposed　Normalized　Difference　Sea　Ice　Information　Index　(NDSIIIOLCI),　which　is　based　on　OLCI　Bands　20　and　21,　can　be　used　to　rapidly　and　effectively　detect　sea　ice　but　is　somewhat　affected　by　the　turbidity　of　the　seawater　in　the　southern　Bohai　Sea.　The　novel　Enhanced　Normalized　Difference　Sea　Ice　Information　Index　(ENDSIIIOLCI),　which　builds　on　NDSIIIOLCI　by　also　considering　OLCI　Bands　12　and　16,　can　monitor　sea　ice　more　accurately　and　effectively　than　NDSIIIOLCI　and　suffers　less　from　interference　from　turbidity.　The　spatiotemporal　evolution　of　the　Bohai　Sea　ice　in　the　winter　of　2017-2018　was　successfully　monitored　by　ENDSIIIOLCI.　The　results　show　that　this　sea　ice　information　index　based　on　OLCI　data　can　effectively　extract　sea　ice　extent　for　sediment-laden　water　and　is　well　suited　for　monitoring　the　evolution　of　Bohai　Sea　ice　in　winter.