The Mont Blanc Ultra Trail, the Holy Grail of ultra-trail running, starts

The 2,500 participants in the 23rd edition of the Ultra-Trail du Mont-Blanc (UTMB), the Holy Grail of ultra-trail running, set off on Friday in Chamonix, two hours later than originally scheduled due to stormy weather in the mountain range.

The main UTMB race is a circuit around the Mont-Blanc massif, passing through France, Italy, and Switzerland. It normally covers 174 km with over 10,000 meters of cumulative elevation gain—equivalent to climbing Mount Everest from sea level and then some.

To ensure runner safety during the stormy conditions, the organizers modified the 174 km route, bypassing high-risk sections such as the Limestone Pyramids. Runners have a maximum time limit of 46.5 hours to complete the course, with strict cutoff times at aid stations along the route to manage runner safety and exhaustion.