Covering two-thirds of the ocean and half of the planet's surface, the high seas are increasingly the focus of commercial activity and conservation ambitions. Contrary to narratives of a lawless frontier, they are governed by a dense network of sectoral institutions for shipping, fisheries, and other industries, although these collectively deal with conservation and sustainable use of biodiversity in a fragmented and uneven manner. These gaps were the subject of nearly 20 years of negotiation, resulting in the adoption of the Agreement on Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction in June 2023. The Agreement was designed to address access and benefit sharing associated with marine genetic resources; the establishment of area-based management tools such as marine protected areas, Environmental Impact Assessments, and capacity building; and the transfer of marine technology. Achieving coherence across public and private governance mechanisms will be a significant challenge as human activity increases on the high seas, but it is key to achieving ocean sustainability goals.