Machapuchare is a 6993 meter/22943 ft high mountain in Nepal, its name means fishtail in Nepali and it is nicknamed the Matterhorn of Nepal. Ascents of this peak are not allowed out of respect for the sacred god Shiva and the only known attempt on this mountain was in 1957 by a British team who retreated 150 meters from the summit having promised not to set foot on the very top. It’s possible, although unconfirmed, that New Zealand climber Bill Denz made an illegal ascent of this peak in the early 1980s, but since he was killed by an avalanche in 1983 we will probably never know for sure.
Mount Kailash is a 6638 meter/21778 ft high mountain in the Tibet autonomous region of China and one of the world’s most sacred mountains. Each year thousands of religious people make a pilgrimage to Mount Kailash, believing that this will bring them good luck; and due to all the religious beliefs surrounding it, climbing on this mountain is forbidden. In 2001 a Spanish team got permission to attempt this peak, but because of international disapproval, the Chinese decided to ban climbing on this mountain and accomplished climber Reinhold Messner condemned the Spanish, claiming “If we conquer this mountain, then we conquer something in people’s souls. I suggest they climb something a little harder. Kailash is not so high and not so hard.”
Muchu Chhish is a 7453 meter/24452 ft high peak in Pakistan’s Karakorum mountain range. This is arguably the highest unclimbed mountain that is legally climbable. The summit is part of a very long ridge of giant mountains that is extremely avalanche prone and a long traverse across this sheer ridge at extreme altitude would be required to reach the summit. Only two attempts have been made on this peak and they both failed well below the summit.
Mount Siple is a potentially active volcano located in Antarctica and reaches a height of 3110 meters/10203 ft. The mountain has no known record of being climbed and if it really is unclimbed then it is one of the most prominent unclimbed peaks in the world. Mount Siple isn’t well known due to its obscure location, its topography has only been measured by a sketch map and any attempt to climb this peak would have to deal with the extreme conditions of Antarctica while being very far away from help in the event of an emergency.