24 heures, 100 km et 12 heures de Nantes

The 24 heures, 100 km et 12 heures de Nantes is an ultra-running race series in Nantes, Loire-Atlantique, held in May. It offers runners four formats within the same event: a 24-hour race, a 12-hour race, a 6-hour race, and a fixed 100 km race. The timed races take place on a 1.4 km course, meaning the challenge involves repeated laps rather than traveling between locations. The starts are staggered throughout the day, with the 24-hour race beginning in the morning, the 6-hour race at midday, the 100 km in the evening, and the 12-hour race at night.