Earth’s youngest ocean still carries India’s name west and east
The Indian Ocean, third-largest of five oceanic divisions, covers about 70,560,000 square kilometres—roughly twenty percent of Earth’s water surface—between Asia, Africa, Australia, and the Southern Ocean. Geologically it is the youngest ocean, succeeding Tethys only about twenty million years ago.
A Latin label, Oceanus Orientalis Indicus, appears by 1515, honouring the subcontinent that pokes into it; before that Europeans spoke of the Eastern Ocean. Ming voyagers such as Zheng He called it the Western Oceans, Greek geographers knew their corner as the Erythraean Sea, and Sanskrit texts used Mahodadhi, great sea, or Ratnakara, mine of jewels. Hindi today says Hind Mahāsāgar.
The 20th meridian east off Cape Agulhas separates it from the Atlantic, and a line south from Tasmania divides it from the Pacific. It holds some 264 million cubic kilometres of water, averages 3,741 metres deep and bottoms out at 7,290. Unlike its two big rivals it does not run pole to pole but is walled in on three sides, and all of it lies in the Eastern Hemisphere, with the 90th meridian crossing the Ninety East Ridge. Australia, Indonesia and India have the longest coastlines, and more than two billion people live in bordering countries.
Its rivers are short, averaging about 740 kilometres, but include the Zambezi, Indus and Ganges–Brahmaputra, which builds the Bengal delta, the largest on Earth. The Suez Canal links it to the Mediterranean without locks, and the Strait of Hormuz leads into the Persian Gulf.
Asia drives the strongest monsoon anywhere, reversing the Somali Current each year. Northeast winds dominate from October to April, and south and west winds from May to October; about 80 percent of India’s annual rain arrives in summer, and failed monsoons once brought civilisations down. This is also the warmest ocean. It warmed about 1.2 °C per century between 1950 and 2020, fastest in the Arabian Sea, and models project marine heatwaves climbing from roughly 20 days a year to 220–250 by century’s end. Reefs, mangroves and seagrass thrive here, and a large share of the world’s tuna is caught in these waters.
Source: Indian Ocean
