Trail O Duc is a mid-December trail event held in Quarré-les-Tombes, a village within the Morvan massif in Burgundy's Yonne department. The event includes a 20 km trail race, a 9 km trail race, an 8.9 km canicross race, and a 9 km walk, allowing runners, walkers, and dog-and-runner teams to participate together.
The routes primarily traverse the Forêt du Duc, featuring wooded paths, undulating terrain, and moderate ascents. The 20 km course presents approximately 520 meters of elevation gain, positioning it as the more demanding option without classifying it as a mountain ultra.