The Barkley is the world’s toughest race you’ve never heard of. With 59,100 feet of climb and decent over 100 miles, it’s considered the most difficult endurance event on the planet. In its 25-year history, only twelve men, the same amount of men who have walked on the moon, have actually been able to finish the race.

Before and after shots of some of the competitors. Look at these faces. These people have stared into the abyss.