The coastal city of Saint-Malo in France is renowned for hosting some of the most spectacular tidal events in Europe, known as the spring tides (grandes marées).
During these extraordinary times, kilometers of beaches emerge and disappear as tide levels change dramatically throughout the day. One may wonder about the science behind this remarkable phenomenon, and what activities are ideal for visitors during both high and low tides.
In this article, I will cover everything you need to know about the high tides of Saint-Malo.
Key Takeaways on the high tides in Saint-Malo:
- The spring tides of Saint-Malo are a magnificent natural phenomenon and some of the largest in Europe
- The high tides are particularly striking and provide an unforgettable experience
The phenomenon of high tides in Saint-Malo
Let’s begin with the basics: a tide is characterized by the rising and falling of sea levels. This change in sea level is caused by the gravitational forces between the moon, sun, and Earth.
Every six hours or so, which means twice a day, the sea level rises, pauses for about 20 minutes, and then falls. After another 20-minute pause, the cycle repeats.
As mentioned before, the amplitude of the tide varies depending on the alignment of the moon, sun, and Earth. When these three celestial bodies are aligned on the same axis, tides are more significant. Thus, there is a high tide at every new and full moon. Consequently, the attraction is weaker during the first and last lunar quarter.
In Saint-Malo, the tidal range, which is the difference between high and low tide levels, can reach up to 14 meters! That’s why people say that the highest tides in Europe occur in Saint-Malo’s bay.
So, how can we determine the height of tides? The answer lies in coefficients!
Tidal Coefficients
To assess the height of a tide, a coefficient is used. It provides information about the tidal range and ranges from 20 to 120. The higher the coefficient, the more substantial the tide. Coefficients above 90 indicate high tides!
However, it’s vital to highlight that coefficients do not indicate the actual water height. They also don’t account for weather conditions. That’s why two tides with the same coefficient can have different heights. We’re not talking about a difference between a 12-meter tide and a 14-meter tide (it will be less), but the difference may still be significant.
Additionally, if a windy day coincides with a high coefficient, the water height can increase even more!
In summary, while coefficients provide a helpful indication, they don’t tell the whole story.
Equinox Tides
Twice a year, in March and September, there is a phenomenon known as equinox tides. These tides are notable because their coefficients reach nearly 120.
During equinox tides, the sea recedes exceptionally far. In Saint-Malo, surprising rocks that are usually hidden become visible on the beach at low tide. In contrast, at high tide, the sea rises so high that it crashes against the breakwaters along the Sillon Beach.
To witness the spectacle of these large tides, keep in mind that Mont Saint-Michel Bay is also an exceptional location!
The Century Tide
On March 21, 2015, a remarkable event occurred which is referred to as the century tide. On that day, the tide reached a coefficient of 119! The tidal range was 14.15 meters, equivalent to a four-story building!
Despite its name, the century tide doesn’t occur only once per century, but rather every 18 years. The next one is scheduled for March 3, 2033.
What to Do at High Tide in Saint-Malo?
High tide can be an amazing spectacle, particularly when it’s windy. The waves often surpass the city walls and sometimes crash onto the road along the sillon. It’s important to be cautious and not get too close to the edge, as waves can easily wash over the walls.
Climb up the city ramparts of the old town for the best view of the high tides!
During the highest coefficients, beaches entirely vanish at high tide. It’s incredible how the landscapes change so drastically in such a short time. Also, places like Fort National or Grand Bé turn into islands during these tides.
What to do during low tide?
Low tide also provides an opportunity to visit attractions like the Grand Bé and Fort National, accessible on foot. Access to these areas must be done with great care so as not to be surprised or even trapped by the rising tide.
If you decide to wander on other islets, rocks or sandbanks, don’t forget to tell someone close to you where you are going if you are alone and bring a cell phone so you can call for assistance if necessary.
Enjoy the view from the remparts, from the hike trail “sentier des douaniers” or from the Pointe du Grouin.
When the tide is low, it’s also the perfect time for shore fishing. Grab your rakes and buckets to collect small crustaceans or shellfish.
In the sand, you might find clams or razor clams, for example. You can also explore the rocks and discover shrimps or tiny crabs.
However, be cautious, as there are certain restrictions to be aware of, such as the size of shellfish that can be collected. Check the regulations to ensure you are following them correctly.
Low tide also provides an opportunity to visit attractions like the Grand Bé and Fort National, accessible on foot. If the tide is exceptionally low, you might even be able to reach Petit Bé!
Significant Tides in Saint-Malo in 2023
Tidal coefficients in October 2023
- Sunday 1: coefficient 108
- Monday 2: coefficient 104
- Tuesday 3: coefficient 91
- Friday 27: coefficient 97
- Saturday 28: coefficient 103
- Sunday 29: coefficient 104
- Monday 30: coefficient 102
- Tuesday 31: coefficient 95
Tidal coefficients in November 2023
- Monday 27: coefficient 90
Tidal coefficients in December 2023
- No significant tides in December!