Mountain Madness interests. While leading Mountain Madness, Fischer became renowned for his ascents of the world's highest mountains made without the use of supplemental oxygen. Fischer and Wally Berg were the first Americans to summit Lhotse, the world's fourth highest mountain (27,940 feet / 8516 m), located next to Mount Everest. He and Ed Viesturs were the first Americans to summit K2, (28,251 feet / 8611m) in the Karakoram of Pakistan without supplemental oxygen. During his stewardship of Mountain Madness, Fischer led social and environmental initiatives to help people in the countries in which Mountain Madness traveled. As the leaders of the
K2 incorrectly showing that K2 was taller than Mount Everest, and therefore the tallest mountain in the world. A corrected measurement was made in 1987, but by that point the claim that K2 was the tallest mountain in the world had already made it into many news reports and reference works. The mountains of K2 and Broad Peak, and the area westward to the lower reaches of Sarpo Laggo glacier consist of metamorphic rocks, known as the "K2 Gneiss" and part of the Karakoram Metamorphic Complex. The K2 Gneiss consists of a mixture of orthogneiss and biotite-rich paragneiss. On the south