The United Nations Convention on the Law of the Sea (UNCLOS) is a comprehensive international treaty that establishes a legal framework for all marine and maritime activities, often called the "constitution for the oceans". Its origin lies in the need to replace the 17th-century concept of "freedom of the seas," which only limited national rights to a narrow belt of water, and to resolve the problem of varying, excessive claims of territorial waters by coastal states. The Convention resulted from the Third United Nations Conference on the Law of the Sea (UNCLOS III), which took place between 1973 and 1982, and it was signed on December 10, 1982, in Montego Bay, Jamaica. It entered into force on November 16, 1994, after receiving the required 60 ratifications.
The Convention, comprising 320 Articles and nine annexes, works by defining distinct maritime zones and the rights of states within them. Key provisions include granting coastal states full sovereignty over their Territorial Sea up to 12 nautical miles from the baseline, subject to the right of innocent passage for foreign vessels. Beyond this is the Exclusive Economic Zone (EEZ), which extends up to 200 nautical miles from the baseline, where the coastal state has sovereign rights for exploring, exploiting, conserving, and managing natural resources. The seabed beyond national jurisdiction, known as "the Area," is governed by the principle of the "common heritage of mankind".
UNCLOS connects to several related institutions it established, including the International Seabed Authority (ISA), which regulates deep seabed mining in the Area, and the International Tribunal for the Law of the Sea (ITLOS), which adjudicates disputes concerning the Convention's interpretation and application. The Convention has been supplemented by implementing agreements, most recently the Agreement on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement), also known as the High Seas Treaty. The BBNJ Agreement was adopted in June 2023 and entered into force on January 17, 2026, becoming the third implementing agreement to UNCLOS and creating a global framework for protecting marine life in the high seas, which was a governance gap in the original Convention.