Défi du Lac de Vioreau

In 1487, following the failed siege of Nantes, King Charles VIII and his regent Anne of Beaujeu established a royal encampment near the Château de Lucinière. This land, once a site of strategic military maneuvering, now serves as the serene backdrop for the Défi Lac de Vioreau. As you swim, you are not merely traversing a 200-hectare reservoir; you are moving through a landscape shaped by centuries of clandestine history and noble defense. The lake itself, the largest in Loire-Atlantique, was engineered to regulate the canal system, providing a stable, expansive arena for the open water community.

The water and the echoes of history

Navigating the waters near the estate, you will find yourself passing close to the 'Allée de Chênes', where tercentenary oak trees stand as sentinels along the shore. This same estate, which later sheltered persecuted Jansenists as a clandestine refuge, became a sanctuary of a different kind during the 20th century. The owners, the Count and Countess Le Gualès de Mézaubran, were recognized as 'Righteous Among the Nations' for hiding Jewish families during the Nazi Occupation. Further along the course, the submerged or hidden traces of the 9th-century 'Curtis Alentis' fort remain a silent reminder of the region's long-standing need to defend against northern incursions. While the water today is peaceful, those familiar with the local calendar often look toward the Natation Nature Abbaretz, held just days before in mid-June, to gauge their early-season form in the region's unique lacustrine environments.

Race day logistics

Organized by Nantes Natation, the Défi Lac de Vioreau offers a spectrum of distances from a 500m initiation loop to a 10km endurance test. With entry fees ranging from 5 to 30 EUR depending on license status and distance, the event is designed to be accessible to a wide range of abilities. The course utilizes the main 180-hectare basin, providing a clear, open environment for swimmers. Participants receive a swim cap, and the event structure—including technical meetings shortly before each start—ensures that the focus remains on the experience of swimming in a significant, historic reservoir. Whether you are aiming for the 10km or the shorter loops, you are swimming in a vital piece of French hydraulic heritage.