Tsomoriri or Lake Moriri (official name: Tsomoriri Wetland Conservation Reserve, Tibetan: ལྷ་མོའི་བླ་མཚོ, Wylie: lha mo bla mtsho), is a lake in the Changthang (literally: northern plains) area in Jammu and Kashmir. The lake is at an altitude of 4,595 m (15,075 ft); it is the largest of the high altitude lakes in the Trans-Himalayan biogeographic region, entirely within India. The lake sits between Ladakh, India to the North, Tibet to the east, and Zanskar in the west.
The lake is fed by springs and snow-melt from mountains on the Changthang plateau. Water enters the lake in two major stream systems, one entering the lake from the north, the other from the southwest. Both stream systems create extensive marshes where they enter the lake. It formerly had an outlet to the south, but this has become blocked and the lake has become land locked. As a result, the water is now becoming saline, The lake is oligotrophic in nature, and its waters are alkaline.