South China Sea, Chinese Nan Hai,  arm of the western Pacific Ocean that borders the Southeast Asian mainland. It is bounded on the northeast by the Taiwan Strait (by which it is connected to the East China Sea); on the east by Taiwan and the Philippines; on the southeast and south by Borneo, the southern limit of the Gulf of Thailand, and the east coast of the Malay Peninsula; and on the west and north by the Asian mainland. The South China Sea and the East China Sea together form the China Sea. The southern boundary of the South China Sea is a rise in the seabed between Sumatra and Borneo, and the northern boundary stretches from the northernmost point of Taiwan to the coast of Fujian province, China, in the Taiwan Strait. It embraces an area of about 1,423,000 square miles (3,685,000 square km), with a mean depth of 3,976 feet (1,212 metres).