Ekiden Chatelaillon - Plage is a road relay held in mid-April along the Atlantic coast in Charente-Maritime, France. It starts at Place Jean Moulin in Châtelaillon-Plage and is connected to La Rochelle. The primary event is an Ekiden marathon, where six runners cover 42.195 km through legs of 5 km, 10 km, 5 km, 10 km, 5 km, and 7.195 km. A Half-Ekiden of 20 km for teams of three is also offered, alongside a corporate challenge for businesses, public bodies, and business clubs.
The marathon course is a single, flat loop with minimal elevation gain (around 2 m), emphasizing pacing, handovers, and team coordination over climbing. The route includes seaside sections and passes through the town, offering both coastal and urban running. Organized by Marathon de La Rochelle Serge Vigot, the event holds an FFA label, allows teams to qualify for French championships, and supports the Nouvelle-Aquitaine regional championship. The main relays are preceded by children's races and a family relay, extending the event's scope beyond the six-runner marathon.