This is processed Conductivity, Temperature, Depth (CTD) data from the Marion Island Annual Relief Voyage on the SA Agulhas II Voyage 024, 06 April to 12 May 2017. The 2017 Marion Relief Voyage offered the fifth opportunity to conduct multi-disciplinary, shipbased marine research focusing on links and interactions between air and sea, ocean physics, chemistry, biogeochemistry and biology, including microbial, planktic and benthic communities on board South Africa’s polar research and supply vessel MV SA Agulhas II en route to, and around, the sub-Antarctic Prince Edward archipelago. The overall aim was to continue contributing to an oceanographic observation and monitoring system directed by South African research institutions in support of South Africa’s needs – and where possible, in support of global requirements of inter alia the Global Oceans Observing System (GOOS), the Southern Ocean Observing System (SOOS), the Convention for the Conservation of Antarctic Marine Living...