This is processed and corrected Conductivity, Temperature, Depth (CTD) data from the Marion Island Relief Voyage on the MV SA Agulhas II Voyage 019, 7 April to 16 May 2016. The 2016 Marion Relief Voyage 019 offered the 4th opportunity to conduct multi-disciplinary, ship-based 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 Resources (CCAMLR), and the Agreement on the Conservation of Albatrosses and Petrels (ACAP).With the declaration on 9 April 2013 of the Prince Edward Islands (PEIs) as South Africa’s first offshore Marine Protected Area (MPA), the outcomes of this cruise will further contribute toward an integrated view and a better understanding of the functioning of the combined island/marine PEI ecosystem. This dataset was processed using older standards which may not align with international best practices and the standards currently adhered to by the Department of Forestry, Fisheries and the Environment (DFFE). The Department is re-processing and replacing data to ensure everything has the same format and is of the same quality and datasets will be marked as obsoleted once that is done. As such the user assumes the entire risk related to the use of these data in its current state and format. DFFE disclaims all warranties of the data whether expressed or implied, including without limitation, any warranties of merchantability or fitness for a particular purpose. For any concerns regarding the data, the user may decide to liaise with the listed PIs who will share their insight on the data quality, where possible. It is also strongly recommended that the user liaises with the listed PIs regarding their proposed projects to mitigate against duplication of research efforts. This dataset was processed using older standards which may not align with international best practices and the standards currently adhered to by the Department of Forestry, Fisheries and the Environment (DFFE). The Department is re-processing and replacing data to ensure everything has the same format and is of the same quality and datasets will be marked as obsoleted once that is done. As such the user assumes the entire risk related to the use of these data in its current state and format. DFFE disclaims all warranties of the data whether expressed or implied, including without limitation, any warranties of merchantability or fitness for a particular purpose. For any concerns regarding the data, the user may decide to liaise with the listed PIs who will share their insight on the data quality, where possible. It is also strongly recommended that the user liaises with the listed PIs regarding their proposed projects to mitigate against duplication of research efforts.