Val Marzon viewed from path connecting refuges Auronzo and Lavaredo, Three Peaks Nature Park, Dolomites, South Tyrol (Alto Adige), Italy

Three hikers at foot of Tre Cime di Lavaredo (Three Peaks of Lavaredo), Three Peaks Nature Park, Dolomites, UNESCO, South Tyrol, Italy

Lago di Cengia, Three Peaks Nature Park, Dolomites, South Tyrol (Alto Adige), Italy

Hikers on path overlooking the Lago dei Piani inferiore, Three Peaks Nature Park, Dolomites, South Tyrol, Italy

Hiker in mist near the refuge Lavaredo, Three Peaks Nature Park, Dolomites, South Tyrol (Alto Adige), Italy

Hikers on path between Locatelli and Pian di Cengia refuges with Punta dei Tre Scarperi behind, Three Peaks Nature Park, Dolomites, South Tyrol, Italy

Aerial view by drone of Three Peaks trail, Oahu Island, Hawaii, United States of America, North America

Three Peaks trail, Oahu Island, Hawaii, United States of America, North America

Three Peaks trail, Oahu Island, Hawaii, United States of America, North America

Ski tour at Hochgrat, Allgäu Alps, Bavaria, Germany, Europe

Auronzo Refuge, Three Peaks hiking trail, Alta Pusteria, Dolomites of Sesto, Italy, Europe

Signposts to Three Peaks Hut, Lavaredo Hut and Auronzo Hut, Tre Cime di Lavaredo, Three Peaks, Dolomites, Italy, Europe

Tre Cime di Lavaredo, Three Peaks Trail, Dolomites, Italy, Europe

Hikers, Three Peaks Cabin, Alta Pusteria, Sexten Dolomites, South Tyrol, Italy, Europe

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.

Three young women running on a trail along the water's edge with mountains in the distance, Anchorage, Alaska, United States of America

Three female hikers on pathway in a mountain meadow with mountain, blue sky and clouds in the background, British Columbia, Canada