An aerial photo shows competitors taking part in the 33rd edition of Marathon des Sables, in the Sahara desert, near Merzouga, southern Morocco, Wednesday, April 13, 2018. Under a hot desert sun and with the desolation of the Sahara all around, about 1,000 competitors from 50 countries took part in this year's Marathon des Sables, or Marathon of the Sands. The 33rd edition of the annual race, considered to be one of the most demanding ultramarathons in the world, finished Saturday after six grueling days and about 250 kilometers (150 miles). (AP Photo/Mosa'ab Elshamy)