TEHRAN, July 25 — The Indian Ocean, the third-largest of the world’s five oceanic divisions, stretches across some 70,560,000 square kilometres, or roughly a fifth of Earth’s water surface. Bounded by Asia to the north, Africa to the west, Australia to the east, and the Southern Ocean or Antarctica to the south—depending on the definition used—it remains the youngest of the oceans, geologically speaking. The Tethys Ocean, which fragmented into the Mediterranean Sea and the Indian Ocean, directly preceded it only about 20 million years ago.
Its distinct features include narrow continental shelves. The average depth stands at 3,741 metres, with a maximum of 7,290 metres.
It is the warmest ocean, a characteristic that exerts a significant influence on global climate through its interaction with the atmosphere. The Indian Ocean Walker circulation governs its waters, generating unique currents and upwelling patterns. Monsoons define the climate across the region.
Ecological and Economic Significance
The ocean supports rich ecological diversity. Important ecosystems include coral reefs, mangroves, and seagrass beds. It hosts a significant portion of the world’s tuna catch and is home to several endangered marine species.
From ancient times, the Indian Ocean has served as a hub of cultural and commercial exchange, playing a key role in early human migrations and the spread of civilizations. In modern times, it remains crucial for global trade, especially in oil and hydrocarbons.
But environmental and geopolitical concerns press on the region. These include climate change, overfishing, pollution, piracy, and disputes over island territories.
Naming and Delimitation
The Indian Ocean has been known by its present name since at least 1515, when the Latin form Oceanus Orientalis Indicus is attested, named after India. Earlier it was called the Eastern Ocean. The modern Hindi name is हिंद महासागर (Hind Mahāsāgar).
In Ancient Greek geography, the region known to the Greeks was the Erythraean Sea. Traditional South Asian geography historically calls it the Mahodadhi, divided into Purvapayodhi (sunrise) and Apara (sunset).
The International Hydrographic Organization delineated the borders of the Indian Ocean in 1953, including the Southern Ocean but excluding the marginal seas along the northern rim. In 2002, the IHO delimited the Southern Ocean separately, removing waters south of 60°S from the Indian Ocean while including the northern marginal seas. The ocean is delimited from the Atlantic by the 20° east meridian, running south from Cape Agulhas, South Africa.
From the Pacific, the boundary is the meridian of 146°49’E, running south from South East Cape on Tasmania, Australia. Its northernmost extent, including marginal seas, reaches approximately 30°N in the Persian Gulf.
All of the Indian Ocean lies within the Eastern Hemisphere. The centre of the Eastern Hemisphere, the 90th meridian east, passes through the Ninety East Ridge. Within these waters lie a number of islands, including those controlled by surrounding countries.
The account indicates that the ocean’s strategic and environmental significance continues to draw attention from regional powers and international actors. Observers will watch how these overlapping concerns—from climate shifts to maritime security—shape the future of this ancient waterway.
