Indian Ocean, third largest ocean, c.28,350,000 sq mi
(73,427,000 sq km), extending from S Asia to Antarctica and from
E Africa to SE Australia; it is c.4,000 mi (6,400 km) wide at
the equator. It constitutes about 20% of the world's total ocean
area. The Indian Ocean is connected with the Pacific Ocean by
passages through the Malay Archipelago and between Australia and
Antarctica; and with the Atlantic Ocean by the expanse between
Africa and Antarctica and by the Suez Canal. Its chief arms are
the Arabian Sea (with the Red Sea, the Gulf of Aden, and the
Persian Gulf), the Bay of Bengal, and the Andaman Sea. The
continental shelf of the Indian Ocean is narrow. Madagascar and
Sri Lanka, the largest islands in the ocean, are structurally
parts of the continents as are Socotra, the Andaman Islands, and
the Nicobar Islands; the Seychelles and the Kerguelen Islands
are exposed tops of submerged ridges. The Laccadives, the
Maldives, and the Chagos are low coral islands, and Mauritius
and Réunion are high volcanic c