This granite islet may seem like it is just 300m away: in fact, it stands 2.5km from the coast, accessible by foot at low tide. Many tourists think they can make the trip in a few dozen minutes and end up being caught by the rising tide. An island of 3,8 hectares, Tombelaine is geologically the twin brother of Mont-Saint-Michel. But the resemblance ends there: half as high, it is covered by a dense bush of impenetrable brambles. There are no houses, only the ruins of a fortress built by the English during the Hundred Years’ War.