Everest confronts the most experienced of climbers with many and significant risks. 

Avalanche

Avalanches are one of the biggest dangers for climber's lives and property.  Snow avalanches occur when the load on the upper snow layers exceeds the bonding forces of a mass of snow causing instability.  When the forces reach breaking point, the layers fall apart causing the avalanche.

Whiteout

Whiteouts occur in storms and blizzards.  There is so much snow, the climber can only see white all around.  This makes it difficult to retrace a route back to camp.  The use of a compass can help if the camp location is known.  

Snow blindness

Without sunglasses at altitude, the sun can burn the cornea causing snow blindness. The best thing to do is keep your glasses or goggles on.  Snow blindness medical drops will considerably speed up recovery.

Falling rocks

Rocks falling from overhead are a cause of death on mountains.

Crevasse falls

A crevasse is space or fracture in a glacier caused by large stresses at or near the glacier's surface. It may be covered by a snow bridge. A danger for mountaineers is falling into a crevasse covered by a weak snow bridge.  It is important for climbers to be trained in crevasse rescue, which is now standard in mountaineering training.

Two or more climbers tie themselves together forming a rope team.  The standard team is three, which means two are available to hold a falling climber.  If a climber falls, the other two dig in to the snow using ice axes and crampons and hold tight until the fallen climber stops moving.  The team can then attempt to pull the fallen climber out.

Judgement

At high altitudes and particularly in the deathzone climbers can become confused due to lack of oxygen.  This confusion can and has caused many mistakes. 

Khumbu Icefall 

The Kumbhu icefall is one of the most dangerous stages of the south route to the summit of Everest.  It is a secion with many crevasses and large towers of if ice, some as large as a house.    This is the only place that requires extensive use of ladders to span the crevasses and the entire icefall requires clipping and unclipping from fixed lines (ropes attached to the mountain).