Twice a day, when the tides go down, this causeway appears to connect the French mainland to the island of Noirmoutier, but cross quickly or the road will disappear, stranding you in the middle of the Bay of Bourgneuf. The Passage du Gois was built upon a strip of silt that just barely elevates it above the surface during low tide for a little over an hour at a time. Crossers often wait too long to get started, bet that they’ll be able to make it across, and lose.
Once it starts flooding, it happens quickly. That’s why there are elevated rescue towers located along the stretch – you might just have to swim over to one, climb up and wait it out. When the tide is low, abandoned, ruined cars can be seen littering the sand.
Each year, runners gather for the Foulées du Gois, a race across the causeway. The road also tends to be covered with seashells, making it a popular destination for both souvenir-seeking tourists and locals who look for edible shellfish.