high seas

The high seas are defined by exclusion. Article 86 of the United Nations Convention on the Law of the Sea applies the term to all parts of the sea that are not included in the exclusive economic zone, in the territorial sea or in the internal waters of a state, or in the archipelagic waters of an archipelagic state. What is left over is roughly two thirds of the ocean's surface, and by volume it holds more than 90 percent of the habitat available to life on Earth.

No state owns that water. Article 87 sets out the freedoms every state may exercise there: navigation, overflight, laying submarine cables and pipelines, building installations the convention permits, fishing, and scientific research. Those freedoms have to be exercised with regard for the interests of other states. The result is a shared space governed by permissions rather than by any single owner.

That openness is why protecting life in the high seas is hard. A coastal state can create a protected area inside its own waters under its own law. Beyond them, protection has to be agreed between states, which is the job the BBNJ Agreement was written to do.