An unclimbed mountain is a mountain peak that has yet to be climbed to the top. Determining which unclimbed peak is highest is often a matter of controversy. In some parts of the world, surveying and mapping are still unreliable. There are no comprehensive records of the routes of explorers, mountaineers, and local inhabitants. In some cases, even modern ascents by larger parties have been poorly documented and, with no universally recognized listing, the best that can be achieved in determining the world's highest unclimbed peaks is somewhat speculative. Most sources indicate that Gangkhar Puensum (7,570 metres (24,840 ft)) in Bhutan or on the Bhutan–China border is the tallest mountain in the world that has yet to be fully summited. Gangkhar Puensum has been off limits to climbers since