Membartsho (alternately spelt Mebar Tsho) is a picturesque pool surrounded by granite boulders, in the fast-flowing Tang Chuu (river) in the Tang Valley, near Bumthang in central Bhutan. Known locally as the Burning Lake, it is a holy site, revered as the place where Pema Lingpa, Bhutan's greatest tertön (treasure finder), discovered several of Guru Rinpoche's hidden terma. According to legend, in the 15th century Pema Lingpa had a dream urging him to go to a particular spot in the Tang Chhu river. After standing on the rocks looking into the depths he discerned there was a temple at the bottom with many doors, one of which was open. He dived in and swam into a large cave where a woman with one eye handed him a treasure chest. As he took it from her he found himself back on dry land.
The local citizens and the ruling Penlop were cynical of his claims, so he invited them to return with him where he would retrieve another terma. Holding a lit lamp he told the assembled crowd "If I am a genuine revealer of treasures then may I return with the treasure and my lamp still alight. However, if I am a devil, may I drown." He dived in. After a while people became nervous that he was taking too long when suddenly he burst out of the water holding a statue, a treasure chest and the lamp in his hands was still alight.
The lake is renowned for its beauty, serenity and spiritual significance as a "Ney". Dr Karma Phuntsho, author of The History of Bhutan, explains: "Natural and spiritual energies and vibes flow from the landscape of such powerful spots, making them conducive environment for spiritual experience. Thus, spiritual persons seek such places in order to speed up and enhance their spiritual practice." It is said that enlightened beings can see the temple at the bottom of the lake.
Pema Lingpa prophesised that one day there would be a great center of learning for women in the center of the Tang Valley and that has come to pass. The site is maintained by the nuns of nearby Pema Tekchok Choling Nunnery, which was founded in 2000 and is Bhutan's first shedra (Buddhist university) for women. It was established by Gangteng Tulku Rinpoche, the ninth reincarnation of Pema Lingpa. The nuns have built a small cupboard near the rickety wooden bridge that crosses the narrowest part of the gorge, where they store butter lamps to make offerings at the sacred site. In many spots around the lake are small conical clay mounds, called tsatsas (tsha tsha). Often engraved with a sacred Buddhist symbol and sometimes containing human ash or bone, these distinctive little sculptures are offerings made as part of religious practices, and can be dedicated to either the living or dead.