It will be a historic day when the High Seas Treaty comes into force this week on 17 January. Officially known as the United Nations (UN) Biodiversity Beyond National Jurisdiction Agreement, this new legal instrument is designed to protect and sustainably use the biodiversity in an area covering half of the Earth and two-thirds of the ocean—the water columns and deep seabeds not under any country’s control. The high seas teem with life, from migrating megafauna in surface waters to ancient deep-sea corals and sponges, which have been largely unprotected. Conversations about the high seas were historically driven by commercial interests, including shipping, industrialized fishing, and increasingly mining and prospecting. After more than two decades of planning and negotiating, the High Seas Treaty, which has been ratified by 81 UN member states, will enable the creation of marine protected areas (MPAs) in this vast wilderness.