Trail de la Vallée du Serein

The Trail de la Vallée du Serein takes place in Treffendel, a commune in Ille-et-Vilaine, Brittany, set within the Serein Valley. This nature and forest trail event, held in early June, offers two race distances: 9 km or 23 km. The 9 km course includes approximately 200 metres of elevation gain, requiring trail running ability without being an extended effort. The 23 km race, the primary event, features around 650 metres of elevation gain, presenting a more demanding option for those seeking a longer route through the valley and forest.