The 2025 Marion Relief Voyage 066 offered the 13th opportunity to conduct multi-disciplinary, ship-based oceanographic research on board the SA Agulhas II en route to, from, and around, the sub-Antarctic Prince Edward Islands (PEIs). The ship-based research was conducted as a joint multi-institutional, multidisciplinary effort with scientists, research technicians, interns and students from the Department of Forestry, Fisheries and the Environment: Oceans & Coasts Research (DFFE-OCR), Department of Forestry, Fisheries and the Environment: Specialist Monitoring Services (DFFE-SMS), Bayworld Centre for Research and Education (BCRE) and the University of Cape Town (UCT), all collaborating to achieve a variety of research and monitoring project objectives. The voyage took place between 17 April 2025 and 27 May 2025.