Approximately half of the Earth's surface consists of the high seas: open-ocean and deep-sea ecosystems beyond the 200-nautical-mile marine jurisdiction of any coastal state. Under the United Nations Convention on the Law of the Sea (UNCLOS), nations hold a duty to protect the marine environment and to conserve the living resources of the high seas.
But the high seas are also open to all nations, and subject to freedoms of fishing and navigation. For such activities to be limited, multilateral agreements are necessary. Such agreements are binding upon their signatory nations, but not upon others.
While there are several multilateral environmental and conservation agreements dealing with the high seas, few establish MPAs as such. Last year, MPA News (2:1) reported on various activities by scientists and governments to support the designation of MPAs in international waters. New information is now available.