Pangong Tso or Pangong Lake is an endorheic lake spanning eastern Ladakh and West Tibet situated at an elevation of 4,225 m (13,862 ft). It is 134 km (83 mi) long and divided into five sublakes, called Pangong Tso, Tso Nyak, Rum Tso (twin lakes) and Nyak Tso. Approximately 50% of the length of the overall lake lies within Tibet in China, 40% in Ladakh, India and the remaining 10% is disputed and is a de facto buffer zone between India and China. The lake is 5 km (3.1 mi) wide at its broadest point. All together it covers almost 700 km2. During winter the lake freezes completely, despite being saline water. It has a land-locked basin separated from the Indus River basin by a small elevated ridge, but is believed to have been part of the latter in prehistoric times.

Historically, the lake is viewed as being made up five sublakes, which are connected through narrow water channels. The name Pangong Tso only applied to the westernmost lake that is mostly in Ladakh. The main lake on the Tibetan side is called Tso Nyak (the “middle lake”). It is followed by two small lakes called Rum Tso. The last lake near Rutog is called Nyak Tso again. The whole lake group was and is still often referred to as Tsomo Nganglha Ringpo  in Tibetan.

There are different interpretations of the meanings of both Pangong Tso and Tsomo Nganglha Ringpo. The Ladakh government website says “Pangong Tso” is Tibetan, meaning “high grassland lake”, however travel books say Pangong means “hollow”. Tsomo Nganglha Ringpo is Tibetan that is interpreted to mean various different but similar meanings — “long, narrow, enchanted lake” by Chinese media sources, “female narrow very long lake” by early European explorers, and “long-necked swan lake” by other modern sources.