Although Tough Mudder has been marketed as the toughest marathon in the world, the Barkley Marathons easily beats it out. A secretive ultramarathon, in its 30 years only 14 people have been able to complete it out of roughly 800 participants to date.
Created by Gary Cantrell, the Barkley Marathons was conceived after learing about Martin Luther King, Jr's assassin James Earl Ray escaping from prison. Wikipedia writes, "Making it only 8 miles (13 km) after running 55 hours in the woods, Cantrell said to himself 'I could do at least 100 miles.'" Although there are two versions (60-mile and 100-mile courses), it is the latter that is the most impressive. Participants climb 59,200 feet of rugged, mountainous terrain in Frozen Head State Park near Wartburg, Tennessee.
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