The Passage du Gois in France, Europe's longest submerged road, disappears under the Atlantic Ocean twice a day. The 2.6-mile route connects the Île de Noirmoutier to the French mainland, and high tides cover it in 1.5 to four metres (five to 13 feet) of water for most of the day.
Drivers can only cross during a short window of about three hours, and the journey takes between 15 and 20 minutes. Nine raised refuge markers stand along the route for people caught by rising water. Officials warn that the road should never be treated as passable when flooded, just because another vehicle has entered it.
Planning Around the Tides
Travel experts at Lapland Famille advised visitors and families to plan trips carefully. Alex Dyer, managing director at Lapland Famille, said: "A tide window can look generous until a meal stop runs late or a child needs an unexpected break.
"I'd keep the bridge route ready and treat the Gois as a bonus, because that removes the pressure to race the final minutes with the sea already on its way back in."
Visitor Experiences and Other Routes
On TripAdvisor, a visitor described the road as "absolutely unique". They said: "I have known the Passage du Gois since I was a little girl; it is absolutely incredible and unique in the world.
"This road is revealed every six hours, depending on the tide. Of course, you absolutely must know the tide times and coefficients to know how much time you have to be able to cross it and not be caught off guard by the sea.
"The island of Noirmoutier was connected for years only by this passage before the bridge in 1971.
"Many people stop there for shore fishing. Magnificent photos can be taken, and every year, there is a race organised against the clock on the Passage du Gois."
Other famous underwater roads in Europe include the Lindisfarne Causeway, also known as Holy Island, and the Strood, both in England. The Lindisfarne Causeway is a three-mile paved road connecting the Northumberland mainland to the Holy Island of Lindisfarne, as the North Sea tides cover the road twice daily. The Strood, in Essex, is covered by water during high spring tides, temporarily cutting access to Mersea Island.
