The mountain is also constantly moving and changing. Glaciers shift, ice blocks can break loose, and deep crevasses can be hidden beneath snow. The Khumbu Icefall, one of the most dangerous sections of the standard route, contains towering blocks of unstable ice and constantly changing terrain. Even walking can become dangerous when exhaustion takes over. After days or weeks of climbing, climbers may have difficulty thinking clearly or controlling their movements.
At extreme altitude, a small mistake can quickly become a major problem. Perhaps the most disturbing part is how difficult rescue can be. Everest is not a place where emergency help can simply arrive in minutes. At very high elevations, helicopters have significant limitations, and rescuers themselves face the same deadly conditions as the people they are trying to save.
