Three participants of the UTMB are running in the hills of Chamonix. The famous peaks of the Mont Blanc range are in the background. The Ultra-Trail du Mont-Blanc (also referred to as UTMB) is a single-stage mountain ultramarathon. It takes place once a year in the Alps, across France, Italy and Switzerland. The distance is approximately 166 kilometres (103 mi), with a total elevation gain of around 9,600 m. It is widely regarded as one of the most difficult foot races in Europe. It's certainly one of the largest with over two thousand starters. The combined participation in all of the events is approaching 10 thousand runners. While the best runners complete the loop in slightly more than 20 hours, most runners take 30 to 45 hours to reach the finish line.

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