Long before the larger Atlantic and Pacific oceans had been well explored, the Indian Ocean was a bustling region of travel and trade. More than 2,000 years ago traders sailed the Indian Ocean to exchange goods. Aided by the strong winds of the winter and summer monsoons, merchant ships used the Indian Ocean to move between India, Africa, Arabia, and the East Indies. The waters of the Indian Ocean reach four continents: Asia to the north, Antarctica to the south, Africa to the west, and Australia to the east. The ocean stretches more than 6,200 miles (10,000 kilometers) from east to west at its widest point. It measures 24,442 feet (7,450 meters) at its deepest point. The Indian Ocean is the third largest of the Earth's oceans. Its total area measures about 28,360,000 square miles (73,440,000 square kilometers). Physical featuresUndersea featuresMany seamounts can be found along the ocean floor. These are extinct volcanoes that rise to heights at least 3,300 feet (1,006 meters) above the ocean floor. They are especially abundant along the floor between Réunion and the islands of Seychelles. The Indian Ocean has a large amount of sediment on its floor. This is material that is carried by the rivers that empty into the ocean. The Indian Ocean has more sediment than either the Atlantic or the Pacific. The ocean's Java Trench is the second longest in the world. It stretches some 1,600 miles (2,560 kilometers) from the western side of the Indonesian island of Java to north of Sumatra. Surface featuresThe largest island in the Indian Ocean is Madagascar, which lies off the east coast of southern Africa. Madagascar and some of the other islands, including Sri Lanka and Socotra, are continental fragments. This means that they once were attached to a continent. Other islands in the ocean, including Sumatra, Réunion, Crozet, Nouvelle (New) Amsterdam, and St-Paul, were formed by volcanoes. Some of the volcanic islands, such as the island group of the Maldives, are coral atolls. These are ribbons of coral reef that enclose lagoons. Other notable coral atolls in the Indian Ocean include the Cocos (or Keeling) Islands and the Chagos Archipelago. The coral atolls are found in the tropical portions of the ocean, which center around the equator. On either side of the Indian subcontinent the Indian Ocean splits into two other bodies of water. To the east it forms the Bay of Bengal, which extends from India across to the Malaysian Peninsula. To the west of India, the Indian Ocean forms the Arabian Sea, which extends westward to Oman and Yemen on the Arabian Peninsula. The Arabian Sea, in turn, branches off into the Persian Gulf. Several important rivers empty into the Indian Ocean. The Ganges, Brahmaputra, Irrawaddy, and Indus flow into ocean from the Indian subcontinent. The junction of the Tigris and Euphrates rivers, known as the Shatt al ?Arab, empties into the Persian Gulf, which carries the waters through the Arabian Sea to the ocean. Toward the southwest, the Zambezi and the Limpopo rivers empty into the ocean from Mozambique in southern Africa. ClimateMuch of the Indian Ocean lies within the tropical and temperate zones. North of the equator, the climate is driven by the monsoon winds. From October through April, these blow in a northeasterly direction, while from May to September the reverse is true. This region is subject to destructive storms known as cyclones that form over the open ocean. They head for shore in a generally westward direction. Further south the winds are generally calmer, though near Antarctica they can be strong. AnimalsSponges, worms, crabs, mollusks, and brittle stars live in the Indian Ocean, as do dolphin, tuna, various sharks, poisonous sea snakes, sea turtles, and large sea mammals. Penguins are found on the coasts of southern Africa, Antarctica, and some of the islands in the extreme south of the ocean. EconomyThe waters of the Indian Ocean are warmer than the waters in the Atlantic and the Pacific. Because of this, only certain kinds of fish can live there. The fishing industry is therefore limited. However, because of its location, the Indian Ocean plays a significant role in shipping and trade, as it has for thousands of years. The ancient trade routes were made possible because of the strong seasonal monsoon winds. The winter monsoons, which blew down from the northeast, carried traders from India and China, armed with spices, silk and cotton cloths, and rare gemstones, to Arabia and Africa, where they could exchange these goods for coffee, ivory, salt, and gold. In the summer, the monsoon winds blew up from the southwest, carrying traders from Africa and Arabia to India and beyond, to Indonesia and China. Trade along the shipping lanes of the ocean continues in modern times. Petroleum and petroleum products now account for much of the trade. In the late 20th century, however, political differences created some tensions among the countries in the region. In 1997, 14 countries bordering the Indian Ocean formed the Indian Ocean Rim Association for Regional Cooperation (IORARC) in order to protect shipping and promote cooperation in trade on the ocean. Environmental issuesWaste from factories and cities along the coast has created a pollution problem in the waters of the Indian Ocean. In addition, there is concern about the amount of petroleum being transported in ships on the ocean. Oil spills from the ships have had harmful effects on the fish and animals that live in the waters. ExplorationThe earliest explorations of the Indian Ocean were made between 3000 and 1000 BC by navigators from India, Egypt, and Phoenicia. Europeans did not begin to explore and travel the Indian Ocean until the 16th century. The Dutch navigator Abel Tasman explored the northern coast of Australia and discovered the island of Tasmania in the 1640s. The southern waters of the Indian Ocean were explored by James Cook in 1772. In the 1800s the Russians started to explore the area as well. In addition to the voyages of discovery, Britain, France, Portugal, and the Netherlands sent fleets to establish colonies on some of the lands bordering the ocean. By the 19th century, Great Britain had gained control of most of the islands in the ocean. British control of the area continued well into the 20th century. After World War II, however, many of these territories gained independence. |