Euronews went to Chamonix, the Mecca of trail running in France, to show you, from the inside, a race from the Ultra Trail du Mont Blanc (UTMB) circuit.
The CCC is a unique challenge that, since its inception as the 'little sister' of the UTMB race, has grown to become one the world's most prestigious ultratrails.
With a total distance of 101km and 6100m of positive ascent, the CCC crosses three countries and gets its name from the initials of three key locations: Courmayer, the starting point in Italy, Champex, the middle point in Switzerland, and Chamonix, the finish line in France.
Follow the adventure in the video above.
And if you want to know all the results, from this and the other races of the UTMB week, follow this link.