Satellite view of Mont Saint-Michel Bay from Saint-Malo to GranvilleSatellite view of Mont Saint-Michel Bay from Saint-Malo to Granville
©Satellite view of Mont Saint-Michel Bay from Saint-Malo to Granville|Contains modified Copernicus Sentinel data (2017), processed by ESA, CC BY-SA 3.0 IGO
The spectacle of the high tides inThe Bay of Mont Saint-Michel

Why do Europe’s highest tides occur in the Bay of Mont Saint-Michel?

From Granville to Saint-Malo, the Bay of Mont Saint-Michel is the setting for a most impressive natural spectacle!

You’ve probably heard that, on the Destination Granville Terre et Mer, you can experience the largest tides in Europe. But why is it here and not elsewhere? Why is the tide weak in the Mediterranean? Why is it magisterial in the Baie du Mont Saint-Michel and in the Chausey archipelago? With these answers, you’ll be able to shine at your aperitif with friends. Feel free to reread the explanation of tidal phenomena in general before reading what follows.

The tides

a round story of bulges

When the moon and the sun act on the oceans, it creates a kind of immense bulge that creates the phenomenon of the tides. In the Atlantic Ocean, which is very deep, there is a huge volume of water. Whereas in the Channel Sea, its smaller neighbor, there is much less depth and therefore less water.

Imagine then that the large bulge of water in the Atlantic Ocean enters the Channel Sea in a matter of hours. The latter then fills up much more significantly, and its water level is then much higher.

Waves connected to the frequency

Mont Saint-Michel

The reliefs of the Normandy coast must also be taken into account. Indeed, when the famous bulges arrive along the Brittany and Normandy coastlines, they can be deflected by the reliefs. For example, the nose of Jobourg in north Cotentin will create deviations that can be felt all the way to Mont Saint-Michel. This is also the case in the Bay of Saint-Brieuc.

The greatest concentration of these waves therefore occurs in the Bay of Mont Saint-Michel like a funnel receiving numerous marine flows. Thus, the entire baie du Mont Saint-Michel, from Cancale to Granville via the Chausey archipelago, is the place in Europe with the greatest tidal range, i.e. the greatest difference in water height between low and high tide.

To better understand all this, there’s nothing like experiencing a crossing of the Bay with a certified guide.