BharatNotes What is Outer Continental Shelf?
The Outer Continental Shelf (OCS), more precisely termed the Extended Continental Shelf (ECS), is the part of a coastal State's continental shelf that lies beyond 200 nautical miles (nm) from the baselines. Under Article 76 of UNCLOS (adopted 1982; entered into force 1994), the continental shelf comprises the seabed and subsoil of submarine areas extending throughout the natural prolongation of a State's land territory to the outer edge of the continental margin, or to 200 nm where the margin does not reach that far.
Where the margin extends beyond 200 nm, a State may establish an outer limit, but it can never be unlimited. Two outer constraints apply: the limit may not exceed 350 nm from the baseline, OR 100 nm beyond the 2,500-metre isobath (depth contour) — and a State may use whichever constraint maximises its area.
Key Features and the CLCS
A State must submit scientific and technical data to the Commission on the Limits of the Continental Shelf (CLCS), a body of 21 experts in geology, geophysics and hydrography based at UN Headquarters, New York. The CLCS issues recommendations; limits set on their basis are final and binding. Crucially, over the OCS a State holds sovereign rights only over seabed/subsoil resources, not the overlying water column, which remains high seas. Under Article 82, a State exploiting non-living resources beyond 200 nm must make payments/contributions to the International Seabed Authority (ISA) for redistribution, especially to developing and landlocked States.
| Maritime zone | Outer limit from baseline | Key rights of coastal State |
|---|---|---|
| Territorial Sea | 12 nm | Full sovereignty (incl. airspace, water, seabed) |
| Contiguous Zone | 24 nm | Enforce customs, fiscal, immigration, sanitary laws |
| Exclusive Economic Zone (EEZ) | 200 nm | Sovereign rights over all resources (living + non-living) |
| Continental Shelf | up to 200 nm (automatic) | Seabed + subsoil resources only |
| Outer/Extended Continental Shelf | beyond 200 nm (max 350 nm or 100 nm past 2,500 m isobath) | Seabed + subsoil resources only; Art. 82 payments apply |
India's Extended Continental Shelf Claim
India filed its first partial submission to the CLCS on 11 May 2009, claiming shelf beyond 200 nm in the Bay of Bengal, Arabian Sea and Indian Ocean. After the CLCS sought modifications, India's Ministry of Earth Sciences lodged revised submissions on 3 April 2025, splitting the Western Arabian Sea claim to add roughly 10,000 sq km in the Central Arabian Sea while excluding the disputed Sir Creek region to avoid the maritime boundary dispute with Pakistan, which had objected in 2021. A successful claim could add a seabed area approaching India's land area (~3.27 million sq km), with potential reserves of hydrocarbons and polymetallic nodules.
UPSC Angle
Master the difference between the EEZ (resource rights over water + seabed) and the continental shelf (seabed/subsoil only) — a recurring Prelims trap. For Mains, connect the OCS to India's blue economy, deep-sea mining, the Sir Creek dispute, and UNCLOS governance through the CLCS and ISA. Foundational concept — no direct PYQ on this exact term; it underpins questions on maritime zones, UNCLOS, and ocean resources.
