Rewalsar Lake, also known as Tso Pema, is a mid-altitude lake located in the mountains of the Mandi district in Himachal Pradesh, India. It is located 22.5 km south-west from the town of Mandi, at an elevation of about 1,360 metres (4,460 ft) above sea level, with a shoreline of about 735 m. Rewalsar Lake is a sacred spot for Hindus, Sikhs and Buddhists, and sacred to Tibetan Buddhists for the Vajrayana practices of Padmasambhava and Mandarava, which are credited for the lake's creation.

Mandi district is one of the central districts of Himachal Pradesh state in northern India. The town of Mandi is the headquarters of the district.