The Southern Indian Ocean Fisheries Agreement (SIOFA) is responsible for ensuring the long-term conservation and sustainable use of the fishery resources in the high seas of the Southern Indian Ocean. SIOFA has had a number of voluntary and interim benthic protected areas since its inception. To formalise these into recognised areas for spatial management, a process was developed to enable the SIOFA members to consider these areas for formal closure. Scientific criteria were established to consider spatial closure proposals and a protocol for future protected area evaluation agreed. The proposals were then considered against the criteria and led to agreement to twelve benthic fisheries closures in 2025. This paper reviews discussions, consultancies and national papers relevant to the development of the Protocol and closures to identify the drivers and challenges leading to agreement, focusing particularly on science contribution. It then reviews the relevance of this for future closures within SIOFA in the context of future High Seas Treaty negotiations.