Membartsho or Mebar Tsho is a holy site, revered as the place where Pema Lingpa, Bhutan's greatest tertön (treasure finder), discovered several of Guru Rinpoche's terma in the 15th century. The pool in the Tang Valley, near Bumthang in central Bhutan is known locally as the Burning Lake, because according to legend, Pema Lingpa had a dream urging him to go to that particular spot in the Tang Chuu 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 dove 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 and 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 dove 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 devout Bhutanese people come here on auspicious days and make a wish upon the butter lamp they put on the water.
To this day, it is still believed that people who did no vice would see extraordinary view when they stand on the rock behind the lake.