Bottleneck (K2) Bottleneck (K2) The Bottleneck is a location along the South-East Spur, known also as Abruzzi Spur— the most used route to the summit of K2, the second-highest mountain in the world, in the Karakoram, on the border of Pakistan and China. The Bottleneck is a narrow couloir, which is overhung by seracs from the ice field east of the summit. The couloir is located only 400m below the summit, and climbers have to traverse about 100m exposed to the seracs to pass it. Due to the height (8200m) and the steepness (50-60 degrees) this stretch is the most dangerous part
K2 incorrectly showing that K2 was taller than Mount Everest, and therefore the tallest mountain in the world. A corrected measurement was made in 1987, but by that point the claim that K2 was the tallest mountain in the world had already made it into many news reports and reference works. The mountains of K2 and Broad Peak, and the area westward to the lower reaches of Sarpo Laggo glacier consist of metamorphic rocks, known as the "K2 Gneiss" and part of the Karakoram Metamorphic Complex. The K2 Gneiss consists of a mixture of orthogneiss and biotite-rich paragneiss. On the south