Mont Saint-Michel
From Openwaterpedia

Le Mont-Saint-Michel, photo by Hartmut Krinitz
Le Mont-Saint-Michel is a tidal island and mainland commune in Normandy, France. The island lies approximately 1 km off France's northwestern coast at the mouth of the Couesnon River near Avranches and is 7 hectares (17 acres) in area. The mainland part of the commune is 393 hectares (971 acres) in area so that the total surface of the commune is 400 hectares (988 acres). As of 2017, the island had a population of 30.