An accident while mountain climbing generally has unexpected and negative consequences. A seemingly small mistake, such as twisting an ankle in loose rocks, can quickly turn into a dangerous situation if the climber is on difficult terrain and is still some distance from the base camp. Climbers can minimize the consequences of these mistakes by traveling in groups, carrying first aid equipment, and being cautious in their route planning. Alpine climbers are also exposed to perils beyond their control, such as hidden crevasses and avalanches, and because of the inhospitable environment of most mountains, they risk exposing themselves to hypothermia and altitude sickness. Experienced mountaineers plan ahead for all contingencies and let others know their destination and planned return time.
Crevasses are deep ice fissures or large cracks within a glacier .
Many times crevasses are hidden under a covering of snow, making them difficult to identify. Their steep, slippery sides make them almost impossible to climb out of without assistance. For this reason, climbers always rope together and secure themselves to each other when traveling on glaciers and snowfields. Should one partner fall in a crevasse, the other can break the fall and then pull the first out. They occur when heavy snowfall accumulates on steep slopes and the underlying snow pack cannot support the new snow's weight.