- The Indian Ocean is the third largest after the Pacific and Atlantic oceans. It covers nearly 20% of the ocean area in the world. It is the only ocean present entirely in the eastern hemisphere.
- The Indian Ocean meets with South Asia to the north, the Arabian Peninsula and Africa to the West, Southeast Asia and Australia to the east, and the Southern Ocean to the south. It joins the Pacific Ocean to the east and southeast and the Atlantic Ocean to the southwest.
- There are fewer islands in the Indian Ocean compared to the Pacific and Atlantic oceans. Famous ones are the Maldives, Madagascar, Sri Lanka, Mauritius, Comoros, Socotra, and Seychelles.
- The Indian Ocean initially formed around 140 million years ago but took its recent shape 36 million years ago. It happened after the collision of the Indian Subcontinent with Eurasia, the separation of Australia from Antarctica, and the western movement of Africa. The Indian Ocean basin is less than 80 million years old.
- The average depth of the Indian Ocean is 12,274 feet (3,741 meters), while its deepest point is 24,442 feet (7,450 meters) in the Java Trench. A research team has found hadal snailfish, sea squirts, and other unusual species at this low point of the Indian Ocean. (Source)
- Indian Ocean has less number of marginal seas than other major oceans (Pacific and the Atlantic). Main seas with strategic significance include the Arabian Sea, the Bay of Bengal, the Andaman Sea, the Red Sea, the Persian Gulf, and the Gulf of Oman.
- The Indian Ocean has the warmest surface temperature among all the oceans. Its minimum and maximum temperatures are 22 C and 28 C, respectively. (Source)
- The Indus and Ganges cones contribute 40% of sediments in the Indian Ocean. Other major sediment-providing areas of the ocean include a zone south of the polar front and basins near continents on the eastern and western sides. (Source)
- The Red Sea and the Persian Gulf (both in the Indian Ocean) have the highest salinity in the ocean world. Their salinity level is nearly 40 grams per liter (g/l), compared to the average ocean salinity range of 33-37 g/l. (Source)
- The Indian Ocean Dipole (IOD) periodically shifts surface temperatures on opposite sides of the Indian Ocean. This pattern has remained consistent since the end of the last Ice Age and causes heavier rainfall and droughts in various parts of the world. It started after a vast ice sheet in North America melted into the North Atlantic Ocean. Climate change can result in more extreme weather in areas bordering the Indian Ocean. (Source)
- The Indian and the western Pacific Ocean have the warmest waters, which has doubled their size since 1900. The temperature in the Indo-Pacific warm pool continuously remains above 28 C and affects the global climate. (Source)
- The monsoon is the change in the direction of the strongest winds in a region. The Indian Ocean has the most prominent monsoon, which blows from cold to warm areas. The summer monsoon (April to September) brings heavy rain to South Asia, while the relatively weaker winter monsoon (October to March) brings rain or dry conditions to Southeast Asia. The Indian monsoon current is one of the few currents in the ocean gyre that change direction.
- The Indian Ocean Experiment (INDOEX) in 1999 showed the transport of high air pollution levels from South and Southeast Asia towards the Indian Ocean. It was due to fossil fuel consumption and biofuel burning, which degrades air quality on a global scale. (Source)
- The Bengal fan in the Indian Ocean is the biggest submarine fan, which occupies almost the entire Bay of Bengal. It is 3,000 km long, 1,430 km wide, and has a sediment thickness of 16.5 km.
- Like other ocean gyres, there are garbage patches in the Indian Ocean. However, it is not thoroughly researched, like the Pacific and Atlantic oceans. More than 99% of litter in the Indian Ocean contains plastic, especially white plastic. (Source)
- Phytoplankton is microscopic marine algae and a primary food for many marine species. Cyclones in the north Indian Ocean give rise to algae in the Arabian Sea and the Bay of Bengal. This phytoplankton bloom is more evident in the post-monsoon than in the pre-monsoon period. (Source)
- 85% of world mangrove species and 47% of mangrove area is present in 30 countries bordering the Indian Ocean. (Source)
- The Indian Ocean has the least number of trenches compared to other oceans. The Java Trench is the second longest after the Peru-Chile (or Atacama) Trench in the eastern Pacific Ocean.
- Countries bordering the Indian Ocean faced two devastating tsunamis in 1883 and 2004. The tsunami on 26 August 1885 by a volcanic eruption killed more than 36,000 in Indonesia. The 2004 Boxing Day Tsunami of more than 9.1 magnitudes took the lives of around 230,000 people in South and Southeast Asia. (Source)
- A comet impacted the Indian Ocean about 2300-2800 BC, the oldest sizeable ocean comet in the past 5000 years. It created mega-tsunami waves and a 29-km Burckle crater. It also affected the climate and earth’s natural systems. (Source)
- The Indian Ocean trade routes have connected Southeast Asia, Arabia, India, East Asia, and East Africa since the third century BC. Seasonal monsoon winds play a vital role in establishing these maritime routes. These trade routes also assist in spreading religions like Hinduism, Buddhism, and Islam. The Portuguese, Dutch, and British extended their empires after the 16thCentury through their hold on the Indian Ocean trade routes.
- The first comprehensive scientific exploration of the Indian Ocean was conducted in 1959, known as the International Indian Ocean Expedition (IIOE). Several countries participated in this project through vessels, shore stations, personnel, and scientists. This expedition continued for several years and is famous for being one of the top multinational efforts in oceanography.
- In 2017, scientists found a submerged continent in the Indian Ocean near Mauritius. According to estimates, the ancient continent “Mauritia” was once between India and Madagascar. However, it started to break up 85 million years ago when India and Madagascar moved apart. The discovery of more continents in the Indian Ocean near Western Australia is also possible. (Source)
- Kerguelen plateau in the Indian Ocean is the longest continuously erupting supervolcano, nearly half the size of the Australian continent. It remained above sea level between 100 million and 20 million years ago and is now more than 1,000 meters below sea level. Volcanic activity in the past has deposited the amount of lava on the seafloor enough for 184,000 Olympic-sized swimming pools. (Source)
- The Ninetyeast ridge separates the eastern and western parts of the Indian Ocean. It is the straightest and one of the longest in the world ocean and is almost free from earthquakes.
- Nearly 40% of the world’s oil supply and 64% of oil trade depends on the Indian Ocean. The main entryways of this oil trade (36 million barrels per day) are the Bab-el-Mandeb and the straits of Hormuz and Malacca.
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