Blue whale, Trincomalee

About Amazing Sri Lanka

Sri Lanka: Location and Adjacent Waters

The southern part of the Indian subcontinent, the Deccan Peninsula, stretches out into the Indian Ocean like a giant tongue, dividing it into two basins. Sri Lanka lies off the tip of this tongue, with unbroken expanses of water – the Bay of Bengal and the Arabian Sea – spread out to east and west. Southward lies the main body of the Indian Ocean.


This position – at the tip of a great continent, yet in the middle of an ocean – makes Sri Lanka a busy crossroads for many kinds of marine life. Just as the island itself is a birdwatcher’s paradise, drawing hundreds of migratory species from Europe and Asia, the waters surrounding it are among the best places in the world to see whales, dolphins and other long-distance travellers of the deep.


Further away are the Chagos-Laccadive Ridge, 750km (400nm) west of Sri Lanka, whose peaks rise above sea level to form the Chagos, Laccadive (Lakshadweep) and Maldive island chains, and Ninety East Ridge, a gigantic submerged mountain range that rises 830km (450nm) east of Sri Lanka and stretches southward as far as the Horse Latitudes.

Sri Lanka India Maritime Boundary

Sri Lankan and adjacent waters in the Northern Indian Ocean (NIO)

Anatomy of an Island
Kalpitiya estuary

Sri Lanka lies within the tropical zone between latitude 5° 55’— 9° 51’N and longitude 79° 41’— 81° 53’E. It has a land area of about 65,600 sq km, bounded by a coastline some 1,800km in length.


The continental shelf surrounding the island and connecting it to the continent of Asia is estimated to cover between 26,000 and 30,000 sq km and supports a variety of highly productive marine ecosystems, while the littoral features a proliferation of estuaries and lagoons. Minerals and organic matter from hundreds of rivers and streams in Sri Lanka and southern India nourish these communities of coastal and marine life.

The Indian Ocean as a whole has a mean depth of 3,900m, increasing to a maximum of about 8,000m. Within the 200-nautical-mile (370km) radius of Sri Lanka’s exclusive economic zone, its maximum depth is about 6,000m. The continental shelf on which the island sits has a mean depth of 75m and forms part of the Asian continent.


Around Sri Lanka it is relatively narrow, rarely extending beyond 22km (12nm), pinching in off Kalpitiya Peninsula near Puttalam, and cut by submarine canyons off Dondra Head, Trincomalee, Batticaloa and several other points along the east coast. The shelf is narrowest off Trincomalee, where a giant submarine canyon makes its closest approach to land, and widest off the Jaffna peninsula at Point Pedro, where it extends outward for 60km (32nm).


Other important oceanographical features around Sri Lanka include Adam’s Bridge, a chain of shoals and sandbars that connects the north of the island with India; the Gulf of Mannar (part of the Laccadive Sea), which separates the two countries and is bounded by Adam’s Bridge to the north and the southern tip of India to the west; and the Bay of Bengal inlet, including Palk Bay and Palk Strait, which also separates the two countries and is bounded by Adam’s Bridge to the south.


Beyond the continental shelf, other ridges and seamounts rise from the ocean floor. In the Laccadive Sea, a mid-ocean ridge and several seamounts lie between the west coast of Sri Lanka and the Chagos-Laccadive Ridge.

Sri Lanka EEZ Map

Source: NHO, NARA

© Howard Martenstyn

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SL Maritime © 2016 Google Earth