This article originated as a paper in a symposium organized by the History Department of Rice University, USA, in April 2024 entitled ‘Hidden Archives of Capitalism and Slavery in the Indian Ocean: State, Business, and Personal Collections’. It provides an overview of known sources to-date relating to slavery in the Indian Ocean region amongst the Prize Papers in the High Court of Admiralty (HCA) collection at The National Archives, London. At present only a small part of the Prize Papers has been catalogued, however, as the Prize Papers Project catalogue this unique ‘accidental archive’ down to document level, more and more traces of slavery will be brought to light. The article provides examples from the Atlantic region of the myriad documents relating to slavery to be found in the Prize Papers. However, it focuses on the activities of the colonial Vice Courts of Admiralty (VCA), where cases relating to the Indian Ocean are most likely to be found. At present such cases are most readily accessible in the recently digitized HCA 45, the collection of bound, printed appeal cases sent by the various colonial VCAs to the High Court of Admiralty in London for adjudication. Despite their printed form, HCA 45 (and the VCAs more generally) have received far less attention from historians, a deficit addressed by this project. The article brings together scholarship on the VCAs, provides an overview of their structures and procedures, contextualizes the judicial, administrative and archival genealogy of the printed appeals, considers their uses and their pitfalls, and using examples from HCA 45, explores the opportunities this collection presents for gaining further insight into slavery in this region.