The 10 km et Semi-Marathon de Trappes is a road race in Trappes, Yvelines, Île-de-France, typically held in late April. Participants can select the 10 km or the half marathon, which measures the standard 21.0975 km. The event schedule is efficient: the half marathon begins first, followed soon after by the 10 km, structuring the morning around multiple races instead of a single mass start.
The course winds through public parks and alongside lakes and ponds, offering a more natural setting than a typical urban circuit. It is also designed for families, with separate races for children and juniors, including a short 1.5 km option. The Mairie de Trappes organizes the event, and the listed entry fees are modest compared to many road races, with distinct pricing for the half marathon, 10 km, and children's races.