The Indian Ocean accounts for about 20% of the water on the surface of the Earth which makes it the third largest ocean in the world. The Indian Ocean has an area of about 70,560,000 square km and is named after India. The important marginal seas, gulfs, straits, etc., of the Indian Ocean, are described below:
21. Bay of Bengal
The northeastern part of the Indian Ocean is known as the Bay of Bengal. Mainland India and Bangladesh lie to the west and north of this body of water. To the east, the Bay of Bengal is bounded by the Indian archipelago of the Andaman and Nicobar Islands and the sovereign nation of Myanmar. The southern boundaries of the bay are formed by an imaginary line running between Sri Lanka and Sumatra’s north-westernmost point. The Bay of Bengal spans an area of 2,172,000 square km. The maximum depth of the bay is 15,400 ft. Several major rivers of South Asia drain into this bay.
20. Palk Strait
The Palk Strait connects the Palk Bay and the Bay of Bengal in the Indian Ocean. It separates Sri Lanka’s Mannar district from the Indian state of Tamil Nadu. The width of the Palk Strait varies between 53 and 82 km.
19. Andaman Sea
The Andaman Sea is part of the eastern Indian Ocean. The Andaman and Nicobar Islands archipelago separates this marginal sea from the Bay of Bengal. The Andaman Sea washes the shores of Thailand, Myanmar, and the Malay Peninsula. The sea extends south till the Breueh Island. The Andaman Sea, its islands, and coral reefs are popular tourist destinations. The sea also supports a thriving fishing industry. The sea also allows easy transport of goods between the coastal countries. The surface area of the Andaman Sea is 600,000 square km and its maximum depth is 13,773 ft.
18. Laccadive Sea
Also known as the Lakshadweep Sea, this water body has India, Sri Lanka, and the Maldives as its basin countries. The warm waters of the sea support great marine biodiversity. The surface area of the Laccadive Sea is 786,000 square km and its maximum depth is 13,553 ft.
17. Gulf of Mannar
The relatively shallow but large bay of the Gulf of Mannar is part of the Laccadive Sea. This bay extends from India’s southeastern tip to Sri Lanka’s west coast. The sea is a significant habitat for the dugong. The Gulf of Mannar has a surface area of about 10,500 square km and a maximum depth of 4,380 ft
16. Strait of Malacca
This strait connects the Indian Ocean to the west with the Pacific Ocean to the east. It stretches for about 890 km between Sumatra island of Indonesia and the Malay Peninsula. The Strait of Malacca is one of the world’s most important shipping lanes.
15. Sunda Strait
The Sunda strait connects the Java Sea and the Indian Ocean and lies between Sumatra and Java islands of Indonesia.
14. Great Australian Bight
This bight is off the southern coastline of mainland Australia. The bight was formed when Gondwana broke apart into Australia and Antarctica about 50 million years back. The coastline of Australia along this bight features high cliffs, surfing beaches, and whale watching opportunities. The waters of the bight have rich marine biodiversity. The Great Australian Bight has been extensively exploited for fishing, whaling, oil and natural gas exploration, and other commercial activities.
13. Mozambique Channel
An arm of the Indian Ocean, the Mozambique Channel stretches between Mozambique and Madagascar. The channel has a length of about 1,600 km and a maximum depth of 10,800 ft.
12. Arabian Sea
The Arabian Sea is a part of the northern Indian Ocean. The sea is bounded by India to the east, Somalia and the Arabian Peninsula to the west, and Iran and Pakistan to the north. The sea encompasses a total area of 3,862,000 square km. The maximum depth of this sea is 15,262 ft. The sea has been and still is a part of important marine trade routes.
11. Gulf of Kutch
An inlet of the Arabian Sea, the Gulf of Kutch washes the shores of the Indian state of Gujarat and divides the state’s Kathiawar and Kutch peninsulas. The Gulf has a length of about 99 miles and a maximum depth of 402 ft.
10. Gulf of Khambat
The Gulf of Khambat extends as a bay of the Arabian Sea and separates Gujarat’s Kathiawar Peninsula from the state’s south-eastern part. Gujarat is a state in western India. The gulf is about 200 km long. A number of major Indian rivers like the Narmada, Tapti, Sabarmati, and others drain into the Gulf of Khambat.
9. Gulf of Tadjoura
This gulf is located in the Horn of Africa near the entrance to the Red Sea. The Gulf of Tadjoura is a productive fishing ground and is a treasure trove for pearl oysters. Most of the coastline of this gulf is part of the territory of Djibouti while a part of the coastline in the south belongs to Somalia. The surface area of this gulf is 1,920 square km and it has an average depth of 3,537 ft.
8. Gulf of Aden
The Gulf of Aden is part of the Arabian Sea and extends from the southern coasts of Yemen in the Arabian Peninsula to the northern coasts of Somalia and Djibouti in Africa. The Bab-el-Mandeb links the Gulf of Aden to the Red Sea. The gulf derives its name from the bustling port city of Yemen, Aden. The gulf is a busy shipping route since it is part of the Suez Canal route connecting the Arabian Sea to the Mediterranean Sea. Over 21,000 ships cross the gulf every year. The Gulf of Aden has a maximum depth of 8,900 ft.
7. Strait of Bab-el-Mandeb
This strait connects the Red Sea and the Gulf of Aden and separates Yemen on the Arabian Peninsula from the Horn of Africa’s Eritrea and Djibouti. This strait is strategically located on the Suez Canal route between the Indian Ocean and the Mediterranean Sea. Large volumes of oil are transported through this strait each day.
6. Red Sea
The Red Sea is an inlet of the Indian Ocean between Africa and Asia. The sea is linked to the Indian Ocean via the Bab el Mandeb strait and the Gulf of Aden. The surface area of the sea is about 438,000 square km. The maximum depth of the Red Sea is 9,970 ft. The sea is noted for its extensive shallow shelves which are rich in corals and other marine flora and fauna. The Red Sea is the northernmost tropical sea in the world. The northern end of the Red Sea has the Gulf of Suez and it terminates in the Suez Canal near the city of Suez in Egypt.
5. Gulf of Aqaba
The Gulf of Aqaba stretches out from the northern part of the Red Sea between the Arabian Peninsula to the east and the Sinai Peninsula to the west. Saudi Arabia, Egypt, Israel, and Jordan are its basin countries. The Gulf of Aqaba has a maximum width of 24 km and a maximum depth of 6,070 ft. The gulf is one of the world’s best diving sites and has rich aquatic biodiversity. Accidental shipwrecks have been deliberately sunk in the area to allow corals to inhabit such vessels and multiply faster.
4. Gulf of Oman
The Strait of Hormuz and the Arabian Sea are connected via the Gulf of Oman. Thus, it is often regarded as a strait instead of a gulf. The Gulf of Oman borders Oman to the south, the UAE to the west, and Iran and a small part of Pakistan to the north.
3. Strait of Hormuz
The Strait of Hormuz connects the Gulf of Oman and the Persian Gulf. It separates Iran in the north from UAE and Oman's Musandam in the south. The strait is one of the most important choke points of the world and is the only passage between the open ocean and the Persian Gulf. Nearly 20% of the petroleum of the world passes through this strait.
2. Persian Gulf
The Persian Gulf is an extension of the Indian Ocean in Western Asia. The gulf is located between Iran and the Arabian Peninsula to the northeast and the southwest, respectively. The Persian Gulf was witness to the Iran-Iraq War between 1980 and 1988. The gulf has an area of 251,000 square km and a maximum depth of 300 ft. The Persia Gulf is rich in fish but its marine habitat has been greatly affected by oil spills and industrialization.
1. Gulf of Bahrain
An inlet of the Persian Gulf, the Gulf of Bahrain washes the shores of Saudi Arabia’s eastern coast and is separated from the rest of the waters of the Persian Gulf by the Qatar Peninsula to the east. The island of Bahrain is located in this gulf. Saudi Arabia is connected to Bahrain by the King Fahd Causeway that runs across the gulf’s western section. The waters of the Gulf of Bahrain are relatively shallow and subject to wide variations in temperature.