Between 3 February and 30 March 2021 the research icebreaker RV Polarstern conducted an extensive multidisciplinary research expedition across the southern Weddell Sea, Antarctica. During the Continental Shelf Multidisciplinary Flux Study (COSMUS) expedition (designated research expedition PS124), the Ocean Floor Observation and Bathymetry System (OFOBS) was deployed 20 times to collect high-resolution seafloor image and acoustic data with a 26-megapixel resolution camera, HD (high-definition) video camera, forward-facing acoustic camera and multibeam side-scan system from heights of between 1.5 and 4.5 m above the seafloor. To localise the collected data, the OFOBS was equipped with a Posidonia transponder for ultra-short baseline position triangulation, an inertial navigation system (INS) and a seafloor-tracking dynamic velocity logger (DVL). The 20 deployments were made across contrasting areas of the Weddell Sea, Filchner Trough, Filchner Sill and Filchner Shelf. Here, we present the full image dataset collected from across the various deployments as well as raw side-scan data and derived high-resolution bathymetric maps produced from these acoustic data after the cruise. All images are available from https://doi.org/10.1594/PANGAEA.936205 (Purser et al., 2021d) and https://doi.org/10.1594/PANGAEA.932827 (Purser et al., 2021a). Acoustic data for all deployments are also available from PANGAEA, with the raw side-scan data available at https://doi.org/10.1594/PANGAEA.939322 (Hehemann et al., 2021b) and forward-facing acoustic camera data at https://doi.org/10.1594/PANGAEA.939341 (Purser et al., 2021c). Seafloor topographic maps derived from the side-scan data are available at https://doi.org/10.1594/PANGAEA.939087