Six days on a raft in the Colca Canyon. This river is the hardest descent in the world, apart from experimental runs performed by professional explorers and teams of guides. Fortunately, the river increases in difficulty, from the teamwork building first day, to the team-testing end. The Colca River has cut a canyon three kilometres deep. This is the deepest in the world, more than twice as deep as the Grand Canyon, and deeper than the gorge of the Yangtzee. It has an average depth of 3.4 kilometres when measured from mountains of Yajirhua (5212m) and Lucerna (4245m) to its bottom. Condors, ten-foot-broad vultures, live volcanoes, and thousand-foot waterfalls draw the eye up, away from the sculpted white stone riverbed and menacing boulders
