Course des châteaux de la forêt de L'Isle-Adam

Course des châteaux de la forêt de L'Isle-Adam is a mid-October trail event in L'Isle-Adam, Val-d'Oise, north of Paris. The name references the local forest and châteaux. Runners select a trail format from distances including 10 km, 13 km, 22 km, and 25 km, varying by edition. The 25 km trail option covers 470 metres of elevation gain, while the 13 km trail découverte offers a shorter off-road race with 270 metres of climbing. A 13 km walking option is also available for those wishing to experience the forest route without competing. The event targets local trail runners, walkers, and individuals seeking an accessible off-road race. The 10 km is the most popular distance, with over 200 participants in a past edition, and the 22 km attracted more than 100. Entry fees are modest: 12 EUR for the 13 km and 16 EUR for the 25 km. Course details indicate rolling forest terrain, not a flat road race, with sufficient climbing on longer routes to necessitate careful pacing.