Simon will run over 250km (156 miles) through endless dunes, over rocky jebels, and across white-hot salt plains. The sun will be his constant enemy with temperatures regularly reaching 50 centigrade. The sand will be his constant companion, clouds of it under feet, sheets of it stinging his eyes and lots of it chafing where it shouldn’t. The long stage has become a legend in itself.
Simon will run out of a Saharan morning, into the dusk and then the dark, many not finishing the 80+km (52 miles) till well into the next day.
He will be enduring all of this to help raise funds for Bowel Cancer research.
To follow Simon's progress go to Lets Beat Bowel Cancer's Facebook and Twitter page.