Gangkhar Puensum ("White Peak of the Three Spiritual Brothers") is the highest mountain in Bhutan and the highest unclimbed mountain in the world at a height of 7,570 meters. The mountain massif lies on the border between Bhutan and Tibet. In the 1980s, four expeditions failed to climb the main peak. Mountaineering has been banned in Bhutan since 2003. en.wikipedia.org/wiki/Gangkhar_Puensum