Yang-tse-Kiang (not "Son of the Ocean," but "River of the Yang-tse" district) is formed by the junction in latitude 26° 30' N. and longitude 102° E. of two rivers which have their rise in Eastern Tibet. Thence it flows with a tortuous course of 3,000 miles into the Eastern Sea at Haimun, a little N. of Shanghai, which is situated in its vast delta. The estuary is 30 miles across, and the tide extends 520 miles, as far as the Po-Yang Lake. The highest treaty-port on the river is Chung-King (opened 1890), nearly 2,000 miles from the sea, and ships of small size can ascend half that distance. Hankow, 700 miles up, is approachable by vessels of 2,000 tons. Nanking stands at the head of the estuary. The river is in flood from May to September, and falls to its lowest in February. It carries down vast quantities of mud, which forms shifting banks and islands, rendering navigation difficult.