The United Nations Convention on the Law of the Sea (UNCLOS) is an international treaty that establishes a comprehensive legal framework for all marine and maritime activities, often called the Law of the Sea Convention. Its origin lies in the need to replace the older 17th-century concept of "freedom of the seas," which limited national rights to a narrow belt of water, typically three nautical miles. The problem it solved was the growing conflict over expanding national claims for resources, fish stock protection, and pollution control in the mid-20th century.
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 was opened for signature on December 10, 1982, in Montego Bay, Jamaica. It entered into force on November 16, 1994, one year after the 60th state ratified it.
UNCLOS works by defining various maritime zones and the rights within them. For instance, it grants coastal states sovereignty over their territorial sea, which can extend up to 12 nautical miles, allowing foreign vessels "innocent passage". It also grants sovereign rights for resource exploration and use within a 200-nautical mile Exclusive Economic Zone (EEZ). The Convention comprises 320 articles and establishes three key institutions: the International Tribunal for the Law of the Sea (ITLOS) for dispute settlement, the International Seabed Authority (ISA) to regulate deep seabed mining, and the Commission on the Limits of the Continental Shelf (CLCS).
A significant recent development is the Agreement on Biodiversity Beyond National Jurisdiction (BBNJ Agreement), also known as the High Seas Treaty, which was agreed upon in 2023 and entered into force on January 17, 2026, after surpassing the required 60 ratifications. This new instrument, which connects to UNCLOS, addresses the conservation and sustainable use of marine life in areas beyond national jurisdiction, a gap in the original Convention, and provides a mechanism to create Marine Protected Areas. The core structure of UNCLOS itself, however, has remained the same, though the 1994 Agreement relating to the implementation of Part XI amended the original provisions on deep seabed mining.