Relative abundances (%) of diatoms from sediment trap samples from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada between April and July 2019 using an automated Gurney Instruments Baker-style, cylindrical sediment trap (aperture 0.032 m2). The sediment trap was deployed at 40-m depth, 30-m above the seafloor and the rotation for the trap was set to 8-day intervals. Diatom quantifications were done using a light microscope (Zeiss Axio Imager.A2 upright research microscope, University of Helsinki) with phase contrast optics at a x1000 magnification.