Les 24h d'Endurance Hermeland is a road ultra series held in Saint-Erblon, located in the heart of Ille-et-Vilaine, Brittany. The races follow the Ise river and utilize time-based durations instead of a set marathon distance: 6 hours, 12 hours, and 24 hours. All races commence at noon, with options for individual participation and relay teams in the longer formats. The official race details indicate target distances of 100 km for the 6-hour races, 150 km for the 12-hour races, and 250 km for the 24-hour races.
The event welcomes adults, competing individually or in teams, requiring a valid medical certificate or an approved federation license. A distinctive feature is the barefoot category, integrated directly into the official rankings, which the organizer states is a first in France. The 24-hour results also feature a broader Circadian Ranking for all runners, regardless of footwear. Prizes are awarded to the top three male and female finishers in each race, with additional awards for the fastest marathon split, 100 km, 150 km, 200 km, and the quickest 1.5 km lap among 24-hour participants.