Trail des Marcassins is an early-season trail race held in Saint-Brice-sous-Forêt, Val-d’Oise. The start and finish are located at Stade de la Solitude - Léon Graffin. Saint Brice Athlétisme presents two races: a 27 km trail beginning at 9:00 with approximately 300 m of elevation gain, and a 17 km trail starting at 9:30 with around 200 m of elevation gain. Registration is limited to 900 participants for both distances, and on-site registration is not available.
The courses traverse the Montmorency forest massif and the Bois des Champeaux, offering a woodland atmosphere rather than a road race setting near Paris. While the elevation gain is moderate, the paths feature a varied rhythm with frequent hills, descents, and some steeper ascents. Sections of the course wind through pastures, where participants might encounter grazing cattle, roe deer, and the young wild boars that lend the race its name, "marcassins".