Heaven Lake of Tian Shan, Alpine lake in Tianshan Mountains, China.

Heaven Lake of Tian Shan, or Tianchi, is a crescent-shaped alpine drift lake on the north side of the Bogda Shan range in Xinjiang, China, about 30 km south of Fukang. It measures roughly 3 km north to south and 1.5 km at its widest, covers 4.9 km² and reaches 105 m at its deepest. Spruce and fir forest covers the slopes around it, with snow-covered ridges above the tree line.

The lake was known in early Chinese texts as Yaochi, meaning Jade Pool, before a Qing official renamed it Tianchi in 1783. That change came as the Qing dynasty was extending its administrative reach into the Xinjiang region.

The Fushou Temple on the shore displays traditional Chinese architecture and remains an active place of worship that visitors can observe today. Kazakh nomads have set up yurt camps in this area for centuries, and some of those camps are still operating around the lake.

The lake is most accessible between May and October, when the mountain roads are open and the weather allows for comfortable outdoor time. Staying overnight near the shore, whether in a yurt or a guesthouse, gives a very different experience from a day trip.

Although Tianchi is known as a single lake, it is actually part of a group of lakes in the area, including Feilong and Qianlong lakes nearby. The water comes from glacial melt off Bogda Peak, which keeps the temperature of the lake very cold even in midsummer.