When is Mont-Saint-Michel surrounded by water? The spring tides

Mont-Saint-Michel is surrounded by water during spring tides, at high tide. It then becomes an island again for about an hour. The rest of the time, it stays linked to the mainland by the bridge-walkway.

When does Mont-Saint-Michel become an island again?

At high tides with strong coefficients. France’s official tourism website, France.fr, puts the threshold at a coefficient above 110. The calendar published by the tourist office lets you find these dates: for example, it shows a coefficient of 110 in March 2027, at around 8:05 am. The tourist office’s times are those of the SHOM for Saint-Malo, to which it advises adding 5 minutes.

See our tide times page for upcoming dates.

How long does the Mont stay surrounded by water?

About an hour at each spring tide. The Établissement public du Mont-Saint-Michel specifies that once the Mont is encircled by the sea, you need to allow 1 hr to 1 hr 30 before you can get back to the walkway. Plan for this wait in your day.

When to arrive to see the tide come in?

One to two hours before high tide. That is the advice of the Établissement public for seeing the tidal bore and getting onto the Mont before it is surrounded by water. France.fr presents the rock as one of the best viewpoints for watching the spring tides.

• Check the time and coefficient of high tide.
• Allow for the journey when you arrive at the car park: a shuttle of about 12 minutes, or 45 minutes on foot from the shuttle stop.
• By bike, note that the parking spaces inside the walls can be flooded by the tide.

Why has the Mont become an island again?

Thanks to the project to restore its maritime character, launched in 1995. It aimed to clear the sediment that was silting up the Mont. The main stages published by the Établissement public:

In February 2015, France.fr noted that the phenomenon had not occurred for more than 130 years.

The role of the dam

The Couesnon dam releases water to help preserve the island character. Each release lasts at most 3 hours and raises the water by about 40 cm, with a maximum height of 6 m behind the dam. The Établissement public publishes the next release times on its weather and tides page.

What is the tidal range in the bay?

Up to 15 metres. The Normandy prefecture and the Écomusée de la baie give this figure for the strongest tides. The tourist office points out that the bay has the highest tides in Europe. To understand coefficients and the tidal bore, read understanding the tides.

During spring tides, the sea also completely covers the bay’s salt meadows, according to the Écomusée de la baie. This is where the lambs of the AOP Prés-salés du Mont-Saint-Michel graze; they then move back inland.

Where to find spring tide dates?

On the tourist office’s tide calendar, which also publishes a 2026 forecast document on flooding risks, and on the weather and tides page of the Établissement public, which shows the day’s tide with its coefficients. Our tides page uses these times.

Is Mont-Saint-Michel always accessible?

Yes, apart from the short time when the sea encircles it. Access to the village is free, day and night, and the bridge-walkway stays open to pedestrians and cyclists 24 hours a day, except in the event of an exceptional prefectoral order. During a spring tide, simply wait for the sea to go back out.

Never go into the bay without a guide: the sea comes in fast there. Outings are made with a guide certified by the prefecture, see crossing the bay.