The Chinese mainland is flanked to the east and south by the Bohai, Yellow, East China and South China seas, with a total maritime area of 4.73 million sq km, and China's mainland coastline measures approximately 18,000 km.

China abounds in rivers. More than 1,500 rivers each drain 1,000 sq km or larger areas. Most of the large rivers have their source on the Qinghai-Tibet Plateau, and drop greatly between source and mouth. The Yangtze, 6,300 km long, is the largest river in China, and the third largest in the world, The Yellow River valley was one of the birthplaces of ancient Chinese civilization.