BADWATER 135, CALIFORNIA USA
Traditionally referred to as 'the world's toughest foot race', Badwater was forced to alter its traditional route through Death Valley in 2013. The Death Valley Park authorities placed a ban on strenuous events taking place during the summer months, when air temperatures (in the shade) reach over 48 degrees. So organisers came up with an alternative route, one with more than 5,200m of cumulative vertical ascent (compared to 3,962 in the previous route), and 3,900m of cumulative descent (compared to 1,433m). While temperature might not reach the sizzling heights of Death Valley (ultra-runner Dean Karnazes once reported that between his team car handing him a cheese sandwich and him eating it, said sandwich became a toastie), the world's toughest foot race just got tougher.
Race facts: The race takes place in July; 135miles(217km); Maximum 48 hours, there is an entry fee. Read more about Run One of the World's 10 Toughest Marathons