Le Tour du Roc à la Nage is an open-water swim in Granville, on the Normandy coast, centered on a simple but demanding concept: swimmers navigate around the rock of Granville. The primary listed event is a 5 km individual race, contributing to the French open-water circuit and the regional Normandy open-water cup. It is not a large-scale mass participation event; one account noted 116 swimmers at the start, and local sources mention several dozen athletes departing from the port. The participants include dedicated amateurs alongside a smaller contingent of professionals.
The race is significantly influenced by the sea, particularly the tide in the bay near Mont Saint-Michel, where the tidal range is crucial. Organizers schedule the start approximately one hour before high tide, aiming for the fastest swimmers to finish near high water. Conditions can be challenging enough that the course has been shortened previously for safety. However, favorable editions may feature low tidal coefficients, clear skies, and water temperatures exceeding 20°C. The event boasts a long history, with over sixty editions held, and its draw lies in the focused field, the exposed sea conditions, and the distinct route around Granville’s rock, as opposed to a conventional buoy course.