25 Bumps Trail

While experienced trail runners might finish the 14.3 km route in 2 to 3 hours, it's a demanding trail. Most people should plan for 3 to 4 hours of effort, or even longer, especially if you're hiking or taking your time to enjoy the scenery.

The terrain is highly varied and challenging. You'll encounter a continuous succession of climbs and descents, often over rocky mounds, sand, unpaved sections, and gravel paths. Expect technical sections with roots, exposed rocks, and even some minor scrambling over boulders. The white, silica-rich sand areas, like the famous "Sables du Cul du Chien," are particularly unique.

No, this trail is consistently described as "difficult" and "very demanding." It requires good fitness and sure-footedness, with some sections needing prior experience similar to alpine hiking. It's an excellent training ground for mountain races, but not recommended for beginners.

The most common starting point for the Circuit des 25 bosses is from the parking area near the village of Noisy-sur-École, specifically at the Rocher de la Justice. This is a popular spot, so arriving early, especially on weekends, is advisable.

The route offers diverse natural beauty and unique geological features. You'll pass by numerous sandstone boulders and rock formations. Notable highlights include Mont Pivot North, Rocher du Guetteur, Jean des Vignes (a viewpoint), and Rocher Guichot. You'll also encounter grottos, ravines, and sandy areas like the "Sables du Cul du Chien".

Spring and autumn generally offer the most pleasant conditions with milder temperatures and beautiful foliage. Summer can be very hot, especially on exposed sandy sections, so an early start is recommended. Winter can be challenging with potentially icy or muddy conditions, requiring appropriate gear.

Dogs are generally allowed in the Forêt de Fontainebleau, but they must be kept on a leash to protect wildlife and ensure the safety of other trail users. Given the technical nature of this specific trail, ensure your dog is fit enough for the varied terrain and potential scrambling.

No, there are no entrance fees or permits required to access the Forêt de Fontainebleau or to hike the Circuit des 25 bosses. It is a publicly accessible forest.

Given the challenging and technical terrain, sturdy trail shoes with good grip are essential. Bring plenty of water, as there are no water sources on the trail, and snacks for energy. A topographic map (like IGN 2417OT) is highly recommended in addition to GPS, as some sections can be tricky despite the red markings. Dress in layers suitable for the weather.

Yes, the route primarily follows the "Sentier des 25 bosses" for 97% of its length. It also briefly intersects with other paths such as "La grande boucle d'Achères" and "Sentier Denecourt-Colinet 16".

The Circuit des 25 bosses is very popular, especially on weekends and public holidays, due to its proximity to Paris. To avoid crowds, consider visiting on a weekday or starting your jog very early in the morning on a weekend. This also helps with parking availability.