DEATH VALLEY NATIONAL PARK, CA JULY 14: Heat waves rise near a heat danger warning sign on the eve of the AdventurCORPS Badwater 135 ultra-marathon race on July 14, 2013 in Death Valley National Park, California. Billed as the toughest footrace in the world, the 36th annual Badwater 135 starts at Badwater Basin in Death Valley, 280 feet below sea level, where athletes begin a 135-mile non-stop run over three mountain ranges in extreme mid-summer desert heat to finish at 8,350-foot near Mount Whitney for a total cumulative vertical ascent of 13,000 feet. July 10 marked the 100-year anniversary of the all-time hottest world record temperature of 134 degrees, set in Death Valley where the average high in July is 116. A total of 96 competitors from 22 nations are attempting the run which equals about five back-to-back marathons. Previous winners have completed all 135 miles in slightly less than 24 hours. (Photo by David McNew/Getty Images)
