The Passage du Gois or Gôa is a causeway between Beauvoir-sur-Mer and the island of Noirmoutier, in Vendée on the Atlantic coast of France. The causeway is 4.125 kilometres long and is flooded twice a day by the high tide. A road runs along the causeway.
Every year, a foot race – the Foulées du Gois – is held across it, starting at the onset of high tide.
Wikipedia https://en.wikipedia.org/wiki/Passage_du_Gois
Official Website http://www.passagedugois.com/
Coordinates 46°55'47.656" N -2°7'29.895" E