Tso Moriri or Lake Moriri “Mountain Lake”, is a lake in the Ladakhi part of the Changthang Plateau (literally: northern plains) in Jammu and Kashmir in northern India. The lake and surrounding area are protected as the Tso Moriri Wetland Conservation Reserve. The lake is at an altitude of 4,522 m (14,836 ft). It is the largest of the high-altitude lakes entirely within India and entirely within Ladakh in this Trans-Himalayan biogeographic region. It is about 16 miles (26 km) north to south in length and two to three miles (3 to 5 km) wide. The lake has no outlet at present and the water is brackish though not very perceptible to taste.
The lake is fed by springs and snow-melt from neighbouring mountains. Most water enters the lake in two major stream systems, one entering the lake from the north, the other from the southwest. Both stream systems include 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 a endorheic lake. The lake is oligotrophic in nature, and its waters are alkaline.