South China Sea

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South China Sea,

western arm of the Pacific Ocean, c.1,000,000 sq mi (2,590,000 sq km), between the SE Asian mainland and Taiwan, the Philippines, and Borneo. It is connected with the East China Sea by the Taiwan Strait. The Gulf of Tonkin and the Gulf of Thailand are its chief embayments. The southwestern part of the sea from the Gulf of Thailand to the Java Sea is an enormous submerged plain called the Sunda Platform; water is generally shallow (less than 200 ft/61 m) throughout this vast area. In contrast, the northeastern part of the sea is a deep basin, reaching depths of up to c.18,000 ft (5,490 m). The Pearl, Red, Mekong, and Chao Phraya are the largest rivers flowing into the South China Sea. Many islands and reefs dot the sea, which is a region subject to violent typhoons. The Paracels, Spratlys, and other islands and reefs in the sea are variously claimed by China, Taiwan, the Philippines, Malaysia, Brunei, and Vietnam. The conflicting claims, important because of the sea's fisheries and oil and natural gas deposits, have increasingly become a source of international tension, especially between China and the others claimants, in the 21st cent. Chinese assertion of its claims was especially aggressive; it converted reefs into islets capable of acting as military outposts.

South China Sea


a semienclosed sea in the western part of the Pacific Ocean, along the coast of East and Southeast Asia, between the Indochinese and Malaccan peninsulas and the islands of Kalimantan (Borneo), Palawan, Luzon, and Taiwan. It is connected by Formosa Strait with the East China Sea in the north, by the Bashi Channel and Luzon Strait with the Pacific Ocean in the northeast, by Singapore Strait with the Indian Ocean in the southwest, and by Karimata and Kelasa straits with the Java Sea in the south.

The South China Sea has an area of 3.537 million sq km, an average depth of 1,024 m, and a water volume of 3.622 million cu km. The shoreline is relatively weakly indented. Major inlets are the Gulf of Tonkin and the Gulf of Siam. The shores are primarily low-lying. The sea has one large island, Hainan. There are many small islands, including Nansha, Sisha (Paracel), and Bunguran (Great Natuna). Most of the small islands are coral islands. Several large rivers empty into the South China Sea, including the Hsi Chiang, the Red River, the Mekong, and the Chao Phraya (Mae Nam or Menam).

The western and southern parts of the sea are occupied by a broad continental shelf, known as the Sunda Shelf, with depths of 30–80 m, dropping to more than 150 m at the margin. In the northeast is a deep basin, with depths of more than 4,000 m in certain depressions. The greatest depth is 5,560 m. Underwater earthquakes and volcanic eruptions are characteristic. In the deeper parts of the sea, the bottom is covered with silt; in the shallower parts, it is covered with sandy silt, with stones and pebbles in some places.

The sea has a tropical climate, with an equatorial monsoon climate in the southern part. Prevailing winds are northeasterly in the winter and southerly and southwesterly in the summer. The average February temperature ranges from 15°C in the north to 25°C in the south; the average August temperature is 27°–28°C. The region receives 2,000–2,500 mm of precipitation a year. Typhoons occur frequently in the summer and fall. A southern current is clearly marked in the western part of the sea during the winter and a northern current during the summer. Currents in the eastern part of the sea are weak and inconsistent. Current velocities are about 1 km/hr. The average surface water temperature in February ranges from 20°C in the north to 27°C in the south, often exceeding 28°C in the Gulf of Siam. August temperatures are 28°–29°C. The salinity ranges from 31.0–33.0‰ in the summer to 31.5–34.0‰ in the winter. The temperature and salinity are virtually constant at depths greater than 2,000 m, measuring 2.3°C and 34.63‰, respectively. Tides are diurnal and mixed, reaching 5.9 m.

Fish are abundant, including tuna, southern herring, sardines, mackerel, drumfish, and eels. Sea turtles and trepangs are also caught. Major ports include Bangkok (Thailand), Hsiangkang, Canton, and Shant’ou (People’s Republic of China), Ho Chi Minh and Haiphong (Vietnam), and Manila (Philippines).


South China Sea

part of the Pacific surrounded by SE China, Vietnam, the Malay Peninsula, Borneo, and the Philippines