Denali (at one point known as Mount McKinley) in Alaska is a monumentally prolific mountain and the centerpiece of Denali National Park. Not only is Denali the highest mountain in North America, but it has the greatest vertical rise of any mountain in the world and a bulk larger than Mount Everest. The mountain is also characterized by extremely cold weather, reaching -100 °F in one measurement. Due to its extreme latitude, the air has less oxygen than equivalently high peaks near the equator, adding to the risk of altitude sickness for climbers. Denali has two significant summits: the South Summit is the highest one, while the North Summit has an elevation of 19,470 feet. Five large glaciers flow off the slopes of the mountain: Peters Glacier, Muldrow Glacier, Traleika Glacier, Ruth Glacier, and the Kahiltna Glacier. By far the most popular climbing route on the mountain is the West Buttress Route pioneered by Bradford Washburn in 1951.