The Course Nature de la Baie d'Isigny is a trail race series in Isigny-sur-Mer, Normandy, offering two distances: 10.5 km and 17 km. It takes place in February, beginning in the morning before the town hall, and is organized by the Association des Marathoniens d'Isigny sur Mer. The event has a limit of 500 participants for both races combined, and uses chip timing.
The routes are approximately 90% off-road, crossing countryside, the sea edge, dikes, polders, and paths within the Norman bocage. The 10.5 km race is named Les Sentiers du Caramel, and the 17 km race is called Les "dix-huitres" Kilomètres du Caïeu, referencing local oysters. The 17 km race includes a cutoff at the 12 km mark; runners reaching this point after 1 hour and 25 minutes will not be classified. Awards are presented to the top three overall finishers and the first finisher in each category. Prizes consist of local products, including oysters, caramels, and camemberts.