The famed explorer is taking on arguably his most grueling challenge yet - a 56-mile run in the 50-degree heat of the Moroccan desert.

Sir Ranulph takes on six-day ultramarathon

71-year-old explorer is aiming to become the oldest Briton to complete the Marathon des Sables to raise money for charity.

Sir Ranulph Fiennes set to begin six-day ultra-marathon

The British explorer will travel across Antarctica during the southern winter, where temperatures can plummet to -90C.