Siula Grande rises 20,814 feet in the Cordillera Huayhuash range in the Peruvian Andes.Nick Waggoner spent a month exploring the backside of the mountain including the treacherous North Ridge made famous by the harrowing descent of Joe Simpson and Simon Yates in 1985 .Waggoner says daily life beneath the 20,000-foot spires was like a dream, a massive amphitheater in the middle of nowhere that was constantly shedding ice and rock, with whole sections of the glacier calving off.