Tombelaine Rock looks like it is very close to Mont-Saint-Michel, but in fact one needs to cover 2.7 km at low tide to reach it. Many tourists think they can make the journey in a few dozen minutes and end up being caught out by the rising tide. This 3.8-hectare granite island is geologically the twin brother of Mont-Saint-Michel. But the resemblance ends there: half as high (it culminates at 45 metres), the rock is a protected natural area covered by an impenetrable bush of brambles.