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UNCLOS: the zones from the coast to the Area

Prelims and MainsCurrent affairs on this: Ocean, polar and earth science missions

The United Nations Convention on the Law of the Sea (UNCLOS), signed in 1982 and in force from 1994, divides the sea into bands measured from a country's baseline, each carrying different rights. The territorial sea, to 12 nautical miles, is sovereign territory subject only to innocent passage. The contiguous zone, to 24 nautical miles, lets the State enforce customs, tax, immigration and health law. The exclusive economic zone (EEZ), to 200 nautical miles, gives sovereign rights over the resources of water, seabed and subsoil, but not sovereignty: all ships and aircraft pass freely. The continental shelf can run beyond 200 nautical miles, to 350 at most, where the geology is proved to the Commission on the Limits of the Continental Shelf. Beyond lie the high seas, open to all, and beneath them the Area, the seabed beyond national jurisdiction, the common heritage of mankind, run by the International Seabed Authority.

The zones of the sea, from the baseline outwards

The zones of the sea from the baseline outwards A cross section from the coast on the left to open ocean on the right. Measured from the baseline: the territorial sea to 12 nautical miles, where the State is sovereign subject to innocent passage; the contiguous zone to 24, for customs, tax, immigration and health; the exclusive economic zone to 200, giving sovereign rights over resources while all ships and aircraft pass freely; the continental shelf, which may run to 350 where the geology is proved to the Commission on the Limits of the Continental Shelf; and beyond, the high seas above and the Area below, the common heritage of mankind run by the International Seabed Authority, where India holds nodule and sulphide contracts. Coast baseline 12 nm 24 nm 200 nm 350 nm Territorial Contiguous Exclusive economic zone High seas Continental shelf The Area India's nodule and sulphide contracts Territorial sea, to 12 nm: sovereignty, subject to innocent passage Contiguous zone, to 24 nm: customs, tax, immigration, health Exclusive economic zone, to 200 nm: resource rights; free passage for all Continental shelf, to 350 nm: seabed rights only, proved to the CLCS High seas and the Area, beyond: open to all; the seabed run by the ISA
Rights shrink from sovereignty to resource rights to nothing as the bands go out; the seabed beyond them belongs to everyone and is run by the ISA.Source: UNCLOS Parts II, V, VI, VII and XI
  • One nautical mile is 1,852 metres, so the EEZ reaches about 370 km from the baseline. India's zones are set at home by the Maritime Zones Act, 1976, and India ratified UNCLOS in 1995.
  • The Area is governed by the International Seabed Authority at Kingston, Jamaica, which grants exploration contracts and is still writing the mining code that would allow exploitation; disputes go to the International Tribunal for the Law of the Sea at Hamburg.
  • India holds ISA exploration contracts for polymetallic nodules in the Central Indian Ocean Basin (since 2002) and two for polymetallic sulphides, on the Central and Southwest Indian Ridge (since 2016) and the Carlsberg Ridge in the Arabian Sea, the first country to hold two, and has applied for a further area. Its Deep Ocean Mission and Samudrayaan are built for this seabed.
  • The high seas above the Area got their own treaty in 2023: the Agreement on biodiversity beyond national jurisdiction (BBNJ), which creates marine protected areas on the high seas, benefit sharing for marine genetic resources and environmental assessment; it entered into force in January 2026 after the sixtieth ratification.
  • The zones are why the same seabed can be a resource dispute: fishing rights end at 200 nautical miles, shelf rights can run further, and nodule mining in the Area needs an ISA contract that only a sponsoring State can back.

Mains: UNCLOS gives India rights over resources to 200 nautical miles and a claim to the seabed beyond, but the deep sea minerals it wants lie in the Area, where India is one contractor among many under rules the ISA has not finished writing.

UPSC has asked

  • Prelims 2022: the zones of the sea under the Law of the Sea, and what a coastal State may do in each
  • Prelims 2021: who licenses seabed exploration in international waters

Further reading: The High Seas Biodiversity Treaty: an introduction (IUCN)

See also: Deep sea minerals · India's deep sea mining programme · Deep Ocean Mission