Gurudongmar Lake is one of the highest lakes in the world. It lies in the district of North Sikkim in the state of Sikkim in India, only some 5 kilometres south of Chinese border. The lake can be reached by road from Lachen via Thangu.
Gurudongmar lake provides one of the source streams of the Teesta River. The source of Teesta, the Tso Lhamo Lake, lies some 5 km to the east. One can seek permission from the army to trek from Gurudongmar Lake to Tso Lhsmo Lake. The lake remains completely frozen in the winter months from November to Mid-May.