Morvan Oxygene Experience is a trail-running series held in Château-Chinon, Nièvre, France, typically in late June. The races utilize the Morvan's forests, natural paths, and mid-mountain terrain, offering distances of 10 km, 15 km, 21 km, and 36 km. A more challenging 28 km trail includes approximately 1,150 m of elevation gain. The atmosphere is informal, reflected in the organizers' mutant-themed phrase “Oxy gènes de mutants,” aligning with a race focused on demanding effort, fresh air, and the rugged Morvan landscape.
The Trifolium format provides a unique element with varied short loops originating from the event center, including both daytime and night race options. Participants can compete individually, in pairs, or in trios, accommodating those seeking a personal challenge or a shared experience. The event also highlights local Morvan culture through live music, evening entertainment, regional beverages, food vendors, prizes from local artisans, and a commitment to waste reduction. The organizers aim to maintain affordable entry fees, contributing to a community-focused, non-commercial feel.