Trail de la Vallée du Serein - 31 km 2026

The Trail de la Vallée du Serein 31 km begins in Treffendel, Ille-et-Vilaine, Brittany, as the longest event in a June trail running schedule. This is a true trail run, not a road race. The 31 km route includes 900 metres of elevation gain and starts in the afternoon, with 21 km and 9 km races scheduled to follow. The course is noted for its technicality, crossing heathland, rocky sections, valleys, streams, and ponds. The event also features a 12 km Nordic walk and races for children. This offers opportunities for local runners, walkers, clubs, families, and newcomers to participate in the Treffendel event through various formats.