Tso Lhamo Lake, High-altitude lake in Mangan district, India.

Tso Lhamo Lake is a glacial freshwater lake at 5,100 m (16,700 ft) in the Mangan district of Sikkim, about 4 km southwest of the Chinese border. It lies on a high plateau connected with the Tibetan Plateau, northeast of the Kangchenjunga range and just north below the 5,495 m Dongkya La pass. The lake covers 106 hectares with a shoreline of 5.89 km, and the Gurudongmar Lake lies some 5 km to the west.

British botanist Joseph Dalton Hooker documented this lake during his Himalayan expeditions and recorded it as Cholamoo Lake in his scientific notes. This early exploration helped map the region geographically during the 1800s.

The lake is known as Cholamoo in Joseph Dalton Hooker's 19th-century botanical writings, and its name also appears as Chho Lhamo and Cholamu. Its outflow, the Lachen Chu, is the right source stream of the Teesta, so the lake is counted among the river's origins. The German name Cholamu-See is used in Alpine-style naming.

The lake lies below the 5,495 m Dongkya La pass and can be reached by road that climbs the Lachen Chu river valley. Because it sits in the border zone with China, visits require official permits from the authorities. The surface lies at 5,014 m, so allow for the altitude.

The lake receives water from three major glaciers - Zemu, Kangtse, and Pauhunri - making it a vital freshwater source at this extreme altitude. This combination of glacier feeds is uncommon and contributes to the water's clarity and quality.