It’s not just the vastness and depth of the Colca that make it so fantastical, it’s the shifts in its mood. There are more scenery changes along its 100km passage than there are in most European countries; from the barren steppe of Sibayo, through the ancient terraced farmland of Yanque and Chivay, into the steep-sided canyon proper beyond Cabanaconde that wasn’t thoroughly explored until the 1980s. Of course one shouldn’t turn a blind eye to the vital statistics. The Colca is the world’s second-deepest canyon, a smidgeon shallower than near neighbor, the Cotahausi, and twice as deep as the more famous Grand Canyon in the US. But, more than that, it is replete with history, culture, ruins, tradition and – rather like Machu Picchu – intangible Peruvian magic.