Namtso or Lake Nam is a mountain lake at the border between Damxung County of Lhasa Prefecture andBaingoin County of Nagqu Prefecture in the Tibet Autonomous Region of China, approximately 112 kilometres (70 mi) NNW of Lhasa.

Geography and Climate
The lake lies at an elevation of 4,718 m, and has a surface area of 1,870 square kilometres. It is the highest salt lake in the world, and largest salt lake in the Tibet Autonomous Region. However, it is not the largest salt lake in Qinghai-Tibet Plateau. That title belongs to Qinghai Lake (almost twice the size of Namtso); which lies over 1,000 km [650 miles] to the north-east in China’s Qinghai province.
Namtso has five uninhabited islands of reasonable size, in addition to one or two rocky outcrops. The islands have been used for spiritual retreat by pilgrims who walk over the lake’s frozen surface at the end of winter, carrying their food with them. They spend the summer there, unable to return to shore again until the water freezes the following winter. This practice is no longer permitted under the Communist Chinese regime in Tibet.
The largest of the islands is in the north-west corner of the lake, and is about 2,100 m long and 800 m wide, rising to just over 100 m in the middle. At its closest point it is about 3.1 km from the shore.
The most remote island is, at its closest, 5.1 km from the shore.
The weather at Namtso is subject to abrupt sudden change and snowstorms are very common across the Nyainqntanglha range.

Other Features
Namtso is renowned as one of the most beautiful places in the Nyainqntanglha mountain range. Its cave hermitages have for centuries been the destination of Tibetan pilgrims. A surfaced road across Largen La at 5186 m was completed to the lake in 2005, enabling easy access from Lhasaand the development of tourism at the lake.
Settlements in the area include Dobjoi, Donggar and Cha’gyungoinba.
The Tashi Dor monastery is located at the southeastern corner of the lake.
Some scenes in the 2002 Hong Kong film The Touch were filmed at the lake.
It is often incorrectly written that this is the highest lake in Tibet, or even the world. This accolade belongs toSengli, in western Tibet [Lat: 30.42, Long: 84.05], which has an altitude of 5,386 m, and a surface area of 92 km2. However, Namtso is the highest salt-water lake in the world.
Namtso Lake was also featured in the BBC TV series: Himalaya with Michael Palin.

This description of Lake Namtso is from Wikipedia.org