Some terms and an illustration that may help with the " Law of the Sea" concept

The drawing shows where national and international waters extend. Please be aware of terms like internal waters, international waters, Exclusive Economic Zone.

The United Nations Convention on the Law of the Sea (UNCLOS), also called the Law of the Sea Convention or the Law of the Sea treaty, is the international agreement that resulted from the third United Nations Conference on the Law of the Sea (UNCLOS III), which took place from 1973 through 1982. The Law of the Sea Convention defines the rights and responsibilities of nations in their use of the world's oceans, establishing guidelines for businesses, the environment, and the management of marine natural resources.

In the early 20th century some nations expressed their desire to extend national claims: to include mineral resources, to protect fish stocks, and to provide the means to enforce pollution controls. Using customery international law principle of a nation's right to protect its natural resources, President Truman in 1945 extended United States right control to all the natural resources of its continental shelf. Other nations were quick to follow suit. Between 1946 and 1950, Argentina, Chile, Peru, and Ecuador extended their rights to a distance of 200 nautical miles to cover their Humboldt Current fishing grounds. Other nations extended their territorial seas to 12 nautical miles.
By 1967, only 25 nations still used the old 3-mile limit, while 66 nations had set a 12-mile territorial limit and eight had set a 200-mile limit. As of May 28, 2008, only two countries still use the 3-mile limit: Jordan and Palau That limit is also used in certain Australian islands, an area of Belize, some Japanese straits, certain areas of Papua New Guinea, and a few British Oversees Territories, such as Anguilla. TheUnited Nations Conference on the Law of the Sea was convened in New York in 1967.

The convention introduced a number of provisions. The most significant issues covered were setting limits, navigation, archipelagic status and transit regimes, exclusive economic zones (EEZs), continental shelf jurisdiction, deep seabed mining, the exploitation regime, protection of the marine environment, scientific research, and settlement of disputes.

Internal waters: Covers all water and waterways on the landward side of the baseline. The coastal state is free to set laws, regulate use, and use any resource. Foreign vessels have no right of passage within internal waters.

Territorial waters:Out to 12 nautical miles from the baseline, the coastal state is free to set laws, regulate use, and use any resource. Vessels were given the right of "innocent passage" through any territorial waters, with strategic straits allowing the passage of military craft as "transit passage", in that naval vessels are allowed to maintain postures that would be illegal in territorial waters. "Innocent passage" is defined by the convention as passing through waters in an expeditious and continuous manner, which is not “prejudicial to the peace, good order or the security” of the coastal state. Fishing, polluting, weapons practice, and spying are not “innocent", and submarines and other underwater vehicles are required to navigate on the surface and to show their flag. Nations can also temporarily suspend innocent passage in specific areas of their territorial seas, if doing so is essential for the protection of its security.

Contiguous Zone: Beyond the 12 nautical mile limit there was a further 12 nautical miles or 24 nautical miles from the territorial sea baselines limit, the contiguous zone, in which a state could continue to enforce laws in four specific areas: pollution, taxation, customs, and immigration.

EEZs: Extend 200 nautical miles from the baseline. Within this area, the coastal nation has sole exploitation rights over all natural resources. The EEZs were introduced to halt the increasingly heated clashes over fishing rights, although oil was also becoming important. The success of an offshore oil platform in the Gulf of Mexico in 1947 was soon repeated elsewhere in the world, and by 1970 it was technically feasible to operate in waters 4000 metres deep. Foreign nations have the freedom of navigation and overflight, subject to the regulation of the coastal states. Foreign states may also lay submarine pipes and cables.

Continental Shelf:The continental shelf is defined as the natural prolongation of the land territory to the continental margin's outer edge, or 200 nautical miles from the coastal state’s baseline, whichever is greater. State’s continental shelf may exceed 200 nautical miles until the natural prolongation ends. However, it may never exceed 350 nautical miles from the baseline.