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James Jackson among the runners at the UTMB Mont Blanc start arch in Chamonix
Ultra · UTMB · August 2025

UTMB Mont Blanc 100M

A 100 mile loop of Mont Blanc through France, Italy and Switzerland, with almost 10,000m of climbing. Snow, hail, rain and blistering sun.

Date
August 2025
Distance
174 km
Elevation
9,920 m
Time
46h 4m 54s
Location
Chamonix, France

The UTMB is the race every trail runner knows: 100 miles around Mont Blanc, through France, Italy and Switzerland, with almost 10,000m of climbing. It came in the middle of my biggest year, five months after the Marathon des Sables and two months after Ironman Nice.

We had every kind of weather the Alps could throw at us: snow, hail, rain and blistering sun. I crossed the line in Chamonix after 46 hours and 4 minutes.

Two months later I was on the start line of the Moab 240.