[1] It is also part of the FIS Marathon Cup and the biggest cross-country skiing event in France.

Participation is open to anyone from the age of 16, and while no licence is required to sign up, the organisers demand a medical certificate to demonstrate the ability to take part in a long-distance skiing event.

[3] The traditional 76 km course connects the villages Lamoura (1120m), Prémanon, Les Rousses, Bois-d'Amont, Le Brassus (Switzerland), Bellefontaine, Chapelle-des-Bois, Le Pré Poncet, Chaux-Neuve, Petite-Chaux and Mouthe (930m).

Difficulties include the ascent to Risoux (the highest point at 1237m), the fast and tricky descent to Bellefontaine and a short but steep ascent before Le Pré Poncet after 65 km.

The area is also renowned for its freezing conditions as temperatures can hit -20 °C and lower.