Passage du Gois is a submersible causeway in the Bay of Bourgneuf, linking the island of Noirmoutier to the mainland in the France. Imagine living on an island and the only road that connects it to the mainland and its filled with water every time the tide. Twice a day, for an hour or two, the tide goes out and the causeway becomes visible and accessible to traffic. For the rest of the day, it remains flooded under 1.3 to 4 meters of water and cannot be used.
Even though causeways such as Passage du Gois exist in other places like Jindo in Korea, the distinctiveness of Passage du Gois lies in its exceptional length of four to five kilometers. In the 18th century, the causeway was much longer because the old dikes were farther from the coast. Therefore in the early days, the only way to reach Noirmoutier was by boat. In 1971 a bridge was built to cross the 700 meter gap between the Ile de Noirmoutier and the mainland, before that there were only two ways to reach the island, either by boat or via the Passage du Gois. This uneven stone paved causeway was first used during the XVI century as the Baie de Bourgneuf gradually silted up.
A word of caution, thoroughly check the tide tables, they are marked on either side of the causeway on large signs because as the area is very flat the tide rises at an incredible rate and many visitors every year get caught out. There are a few balises large sturdy wooden towers, which one can climb and wait until you are rescued or the tide falls again. Since 1986, an unusual race across the causeway (The Foulées du Gois) is held every year. In Past 1999 Passage du Gois was also used by Tour de France bicycle race.
People went on foot over the sand-banks to the island of Noirmoutier. Much later they have made a paved road. In those days a lot of accidents took place, because of the quickly rising water. This is the reason why rescue piles have been built. Anyone who is surprised by the rapidly rising water can climb in one of these rescue piles. The causeway also attracts a lot of shell seekers. They are looking for the edible shells. With low tide you will see the French on the sea banks with their head to the ground in search of all sort of edible sea shells, which they will be eating at lunch with a delicious glass of the local white wine.
Crossing the causeway is considered perilous. Although tide times are precisely marked on either side of the causeway on large signs, the water comes in at an incredible rate and many visitors get caught out every year. Elevated rescue towers are located all along the Passage du Gois for those caught between the tides. One can climb these towers and wait until they are rescued or the tide falls again.
Today the causeway attracts thousands of visitors a year to watch the twice daily, it remains flooded under 1.3 to 4 meters of water and cannot be used and uncovering of the 4.5 KM of road as it miraculously appears from the sea during the ebbing tide. Visitors come to walk, cycle or drive across the Gois the locals also come to fish ‘by foot especially at low spring tides when the vast expanses of sand which are rich in all manner of shell fish are exposed.