The Bottleneck is a narrow couloir, which is overhung by seracs from the ice field east of the summit. The couloir is located only below the summit, and climbers have to traverse about exposed to the seracs to pass it. Due to the height of , and the steepness of 50 to 60 degrees, this stretch is the most dangerous part of the route. According to AdventureStats, 13 out of the last 14 fatalities on K2 have occurred at or near the Bottleneck.