Nage ta Seine — L'Île-Saint-Denis

Nage ta Seine takes place on September 6, 2026, at L’Île-Saint-Denis, offering a range of distances including 250m, 500m, 1,500m, and 3,000m, alongside an aquathlon format. Swimmers gather along the quays for a river event that utilizes the specific flow and environment of the Seine. Entry fees are set at 10€ for shorter distances and 15€ for the longer challenges and the aquathlon, with timing chips provided in the race kit. Wetsuits are authorized for all participants, while fins, snorkels, and flotation aids remain strictly prohibited to maintain the competitive integrity of the river crossing.

The river environment

While today's course offers a controlled swimming environment, the ground beneath the Seine reflects the geological cycles of the Paris Basin. This area is built upon sedimentary layers including Lutetian limestone and sands, remnants of ancient tropical seas and lagoons that defined the Eocene epoch. The location derives its character from the Seine, a river with a history of significant floods and strategic defenses, such as the bridges used during the Viking siege to control the waterway. The geography here recalls the original Lutetia settlement, where the name itself, rooted in the Celtic *luto-*, reminds us that this was once a marshy expanse. Those looking for further swimming opportunities in the region can find the EDF Aqua Challenge Paris Seine or explore the courses at the Buttes-Chaumont event in September. Just as the historic Traversée de Paris race once drew crowds along the urban riverfront, this event continues the tradition of engaging with the city’s aquatic arteries. The course is also a reminder of the industrial and military landscape, with structures like the École Militaire representing the architectural legacy visible from the broader Parisian river axis.