The Trail du Viroin begins and ends in Nismes's communal park, offering four distances: 10 km, 20 km, 35 km, and 44 km. The shortest route is a genuine off-road challenge with approximately 250 metres of elevation gain, while the 44 km marathon ascends about 1,500 metres.
All courses are contained within the nature park, with significant portions also located in the national park: around 80% for the 10 km, 75% for the 20 km, 87% for the 35 km, and 91% for the 44 km. The 20 km and 35 km events are part of the Challenge des Trail de la Foret du Pays de Chimay, attracting participants from that series alongside those selecting a single distance for the event.