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 been a source of international tension at times.