These rivers can also be classified as exterior and interior rivers. The Yangtze, the longest in China and even in Asia, is the third-longest in the world. The Yellow River, 'Mother River of the Chinese People', is just behind the Yangtze, both flowing into the Pacific Ocean. The Yarlung Zangbo River belongs to the Indian Ocean water system, and the Irtysh River to the Arctic Ocean. On the other side, the interior rivers drain less area than the exterior ones.
Lakes are also important. The areas with the most lakes are the Middle-Lower Yangtze Plain and Qinghai-Tibet Plateau. Many lakes in the northwest are salty. Qinghai Lake, a beautiful natural salt-water lake, is the largest. In southeast China, most lakes are fresh water. Poyang Lake, Dongting Lake , and Taihu Lake are all fresh water lakes.
These provide China with precious resources such as aquatic products, petroleum, natural gas, mines and renewable resources including tide power.