Extreme Marathons

Considered the toughest foot race on Earth, competitors must carry all personal belongings and food for the entire event in their backpack.
Pierre Verdy / AFP / Getty

Marathon des Sables, Ouarzazate, Morocco
Considered the toughest foot race on Earth, competitors must carry all their personal belongings and food for the entire event in a backpack. As of 2007, two competitors have died during the race.

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