Death Valley ultra-marathon

A crew member squeezes wet sponges over Oswaldo Lopez of Madera, Calif. during the AdventurCORPS Badwater 135 mile ultra-marathon race in Death Valley National Park, Calif., July 15, 2013.

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.

A competitor passes the unofficial thermometer at during the Badwater ultra-marathon, July 15, 2013.

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.

Double amputee Chris Moon of the U.K. runs in the Badwater ultra-marathon, July 15, 2013.

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.

Oswaldo Lopez of Madera, Calif. is cooled by his crew as he runs in Badwater ultra-marathon, July 15, 2013.

A crew member carrying a water spray bottle and a runner endure blowing dust in strong winds near Stovepipe Wells during Badwater ultra-marathon, July 15, 2013.

Heat waves rise near a heat danger warning sign on the eve of Badwater ultra-marathon, July 14, 2013.

Runners gather at Badwater Basin for the start of the race, July 15, 2013.

The first of three waves of runners start at the Badwater ultra-marathon, July 15, 2013.

Runners endure blowing dust and strong winds near Stovepipe Wells during the Badwater ultra-marathon race, July 15, 2013.

Lisa Smith-Blatchen of Driggs, Idaho receives first aid foot maintenance at Townes Pass as night nears during the Badwater ultra-marathon, July 15, 2013.

Edwardo Calisto of Brazil runs near Panamint Springs as night falls during the Badwater ultra-marathon, July 15, 2013.

Oswaldo Lopez (C) of Madera, Calif. and Carlos Alberto of Portugal (R) run wearing headlamps near Panamint Springs as night falls during the Badwater ultra-marathon, July 15, 2013.

Oswaldo Lopez (near L) of Madera, Calif. and Carlos Alberto of Portugal (near R) run wearing headlamps near Panamint Springs as night falls during the Badwater ultra-marathon race, July 15, 2013.

Oswaldo Lopez (L, #1) of Madera, Calif. and Carlos Alberto of Portugal (C, #61) run near Panamint Springs as night falls during the Badwater ultra-marathon, July 15, 2013.

A lone competitor runs by headlamp as night falls during the Badwater ultra-marathon, July 15, 2013.

Lisa Smith-Blatchen of Driggs, Idaho receives first aid foot maintenance during the Badwater ultra-marathon, July 15, 2013.

Recreational vehicles pass runners in the Badwater ultra-marathon, July 15, 2013.

Runners pass a heat danger warning sign during the Badwater ultra-marathon race, July 15, 2013.