Competitors warm up at the bivouac during a sandstorm on the eve of the start of the 33rd edition of the Marathon des Sables in the Moroccan Sahara desert in Timgaline, central Morocco, on April 7, 2018. The 33rd edition of the marathon is a live stage 250 kilometres race through a formidable landscape in one of the world's most inhospitable climates. / AFP PHOTO / JEAN-PHILIPPE KSIAZEK