The Marathon des Sables is considered one of the toughest races on earth and rightfully so. Each year, over 10,000 (probably slightly unhinged) competitors from across the world compete in the ultimate challenge - a 230km race, set over a 6 day period, deep within the Sahara desert in Morocco.

This year will be the 23rd edition, running from 28th March - 7th April, 2008. All runners are self-sufficient and must carry all their own equipment, food and kit during the entire race. Conditions can be pretty extreme, with competitors having to battle scorching heat, sand storms and probably some pretty nasty blisters.

If your eco-conscience is the only thing stopping you from getting your running shoes on, fret not, as the organisers of the event are extremely conscious of environmental issues and take drastic steps to ensure that there is no damage to the Sahara. For example, all runners are issued with individual numbered water bottles, marked with their personal official entry number. If any bottles or lids are found discarded in the desert, time will be deducted from the competitors overall time.

Up for the challenge? For further info on the event, please see the Sahara Marathon website.