The 31st Marathon des Sables kicked off on Sunday (April 10) in Morocco's southern city of Merzouga with the participation of 1,100 runners from all over the world. Dubbed as the toughest footrace on Earth, participants of this race must be self-sufficient and carry everything they need in a pack. Water is rationed and a tent (bivouac) is provided each evening, which must be shared with seven other participants. Over 30 years, about 19,000 runners have taken part in this marathon.