Each year in the Ozarks of Arkansas, at a place called Horseshoe Canyon Ranch, an incredible thing happens: hundreds of rock climbers from around the world show up for a grueling competition. It's called Horseshoe Hell, and climbers spend 24 straight hours seeing who can climb the most routes without stopping. Grueling, yes. But it's also a massive party and a ton of fun. This year, the dates are September 20-24.