Connecting the island of Noirmoutier with the Gulf of Burnёf in western France, the Passage du Gois road is unique in its own way. It surfaces only twice a day for a couple of hours, after which it sinks below water as a result of rising tide. For the most part of the day, it remains engulfed in waves around 4 to 13 feet in height.
The island, according to residents, was originally accessible only via boat. Over time, however, the Bay of Bourgneuf silted, giving rise to a slightly elevated causeway. First mentioned on a map back in 1701, the pathway has long been used by people and animals to reach Noirmoutier from the other side. In about 1840, regular services by horseback were started for carrying people across the water.
More recently, the passageway has been declared drivable, albeit only twice every day. For added safety, special panels have been installed to inform passengers whether the road can been traversed by car at any particular time of the day. Authorities have also constructed raised rescue towers for those stranded in the midst of high tide.
Via: My Modern Met