Atacama desert in Chile

“The Atacama Crossing is a 250km foot race across the Atacama desert in Chile which is the driest place on earth and a landscape that bears the closest resemblance to the surface of Mars of any place on earth.  Temperatures range from below freezing at night to over 40 degrees during the day and the altitude ranges between 2500m to 3500m above sea level making the air a tad thin.  The terrain ranges from a rock strewn dry seabed like stretches, to coral like salt flats, to crud resembling a ploughed field to the obvious soft sand dunes.  The race involves crossing all of this and attempting to run some of it as well as climbing what seems like endless escarpments, crossing rivers, descending huge powder like sand dunes and well as navigating a dark mining tunnel with a strategic rock to catch you out half way!  The first four stages are more than 40kms and the long day is 77 k m followed by a little 10 km to finish but it is the back to back nature of it which is a killer.  The main challenges are hydration and nutrition a managing to stop ones feet falling apart quite apart from sheer exhaustion.  Competitors carry all their own food for the whole race and are only provided with water rationed to nine litres of cold a day for drinking and hot water for the fried dried food that everyone lives on and find a struggle to get down by the end.  Washing with the water rations is forbidden!