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 a "constitution for the oceans". The concept is a single, unified legal regime governing the world's oceans and seas.
The Convention resulted from the Third United Nations Conference on the Law of the Sea (UNCLOS III), which took place between 1973 and 1982. It was opened for signature on December 10, 1982, in Montego Bay, Jamaica, and entered into force on November 16, 1994, after Guyana became the 60th nation to ratify it. The problem it solved was the lack of a clear, universally accepted legal order, replacing the older concept of "freedom of the seas" and the four separate treaties of the 1958 Convention on the High Seas. The need arose from varying claims over territorial waters and the desire to manage resources like oil and fish stocks.
UNCLOS, comprising 320 Articles and nine annexes, works by dividing the ocean into distinct maritime zones. A coastal state exercises full sovereignty over its Territorial Sea, which extends up to 12 nautical miles from the baseline, subject to the right of "innocent passage" for foreign vessels. Beyond this is the Contiguous Zone, extending a further 12 nautical miles (up to 24 nautical miles from the baseline), where the state can enforce laws on customs, immigration, and sanitation. The Exclusive Economic Zone (EEZ) extends up to 200 nautical miles from the baseline, granting the coastal state sovereign rights for exploring, exploiting, conserving, and managing all natural resources, while other states retain the freedom of navigation and overflight. The seabed beyond national jurisdiction is designated as "the Area" and is governed by the principle of the "common heritage of mankind".
The Convention is connected to the International Tribunal for the Law of the Sea (ITLOS), which resolves disputes concerning its interpretation and application, and the International Seabed Authority (ISA), which regulates deep seabed mining in the Area. A significant recent change is 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. This agreement, which entered into force on January 17, 2026, acts as an instrument under UNCLOS to fill legal gaps regarding marine biodiversity conservation on the high seas, notably by providing a mechanism for establishing Marine Protected Areas. The original framework of UNCLOS remains, but the BBNJ Agreement introduces new obligations, such as mandatory Environmental Impact Assessments for activities in international waters.