The 2016 edition of the Ultra-Trail du Mont-Blanc (UTMB) mountain race, which will take place on Aug. 22-28, has received 5,471 registration requests. Since its creation in 2003, when there were 700 runners registered, the success of the race has constantly grown. In order to respect a fragile mountain environment, since 2005 the organizers have decided to limit the number of runners which will finally participate to 2,300.