“Comrades on the Colca: A Race for Adventure and Incan Treasure in One of the World’s Last Unexplored Canyons,” by Eugene Buchanan (Independent Publishers Group, October 2016) As the sole kayaker among a team of adventurous yet boatless Poles exploring the world’s deepest gorge, Steamboat Springs’ Eugene Buchanan was overworked and stressed. He was ferrying gear and clamoring explorers down the 11,000-foot-deep Colca Canyon in Peru when he came upon well-equipped strangers.