Pangong Tso, Soda lake at India-China border, Himalayas.

Pangong Tso is a soda lake sitting at the India-China border high in the mountains at about 4250 meters elevation. The water shifts in color throughout the day depending on light and angle, ranging from blue to green, and the lake stretches for over 100 kilometers across the landscape.

Pangong Tso once drained toward the Shyok, an Indus tributary, until a natural dam blocked the outlet; silt deposits show the lake has since dropped about 5 metres. The Khurnak Fort on the northern shore has been held by Chinese forces since 1952. On 20 October 1962 the lake became a combat zone in the Sino-Indian War, and the Line of Actual Control set during that war divides it into Indian, Chinese and disputed sectors.

The name Pangong Tso comes from Tibetan སྤང་གོང་མཚོ, roughly "lake of the high meadows"; a second Tibetan name, མཚོ་མོ་ངང་ལྷ་རིང་པོ, means "long ocean of the divine region". In the 2000s the lake's shores served as a location for the Bollywood film 3 Idiots, and the lake is being proposed as South Asia's first transboundary Ramsar wetland.

To visit this place, travelers need special permits which are usually only available during the warmer months when roads are open and safe. The best time to travel is from May to September when winter has passed and roads are clear of snow and ice.

The lake has no outlet: it once drained toward the Shyok, a tributary of the Indus, until a natural dam blocked the channel. Silt deposits show the water has dropped about 5 metres in geologically recent times. Two streams enter on the Indian side, forming marshes along the shore.