The dataset contains megafaunal image annotation data from Penumbra Site 10, a hydrothermal vent site on the South East Indian Ridge. The underlying image material was collected during the INDEX 2023 expedition with RV Sonne and the remotely operated vehicle ROPOS. Images were annotated manually in BIIGLE 2.0 to record visible megafaunal taxa within the annotated image area. For each image, annotation labels were assigned to taxonomic groups where possible, and the number of individuals per annotation category was recorded. The dataset includes image-level event metadata, model area assignments for three distance areas around active chimneys, FW5, FW10 and FW15, corresponding to 0 to 5 m, 5 to 10 m and greater than 10 m distance from active chimneys, taxonomic identifications where available, annotation labels, numbers of individuals per image and annotated image area. These data were used as image-based abundance input for estimating megafaunal standing stock and parameterizing the linear inverse food-web models associated with the study.