Although not as well-known as Mount Everest, K2 is the second highest mountain on earth and is arguably the most dangerous to climb.  In addition to the lack of oxygen experienced at such high altitudes, all routes to summit K2 are steep with significant exposure.  This exposure, combined with the mountain's propensity to experience extreme storms lasting for days, make for a deadly combination.  The extreme terrain and unpredictable weather leave little to no margin for error.