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Baïnes, these fascinating and terribly dangerous natural phenomena on our beaches

Have you ever heard of baïnes? These natural swimming pool phenomena cause numerous accidents every year on our West Coast beaches in France and on the other side of the world, particularly in Australia.

So in this article we’re going to take a look at how they work, what makes them so dangerous and how to protect yourself from them ?

What is a baïne?

Baïnes, a Gascon term meaning ” petite bassine “, are natural basins formed in places with special conditions, where the tidal phenomenon must be strong, the place relatively well captures the swell and the difference in level is small.

As you know, our fine sandy beaches change at the whim of the tides, winds and heavy swells that affect our coastline. It’s exactly the same for the baïnes, which are constantly on the move.

Surfers use the baïnes to get over the line up.

How are they formed ?

When the swells that form waves break on our beaches, they gradually carry sand out to sea, forming sandbanks as the tides change. Their configurations sometimes bring us world-class waves.

When the tide goes out, the water between the beach and the sandbank digs a gap in the latter. The tidal phenomenon will then cause the sandbank to grow and create a basin, known as the baïne. Each baïne is different in size, and some can be several metres deep depending on the strength of the swell and the tidal range.

How they work 

Baïnes may seem harmless to most bathers because they are so calm. However, the process begins underwater !

At low tide, the basin is virtually empty, so bathers, and children in particular, can swim there without fear.

However, when the tide rises, the bay near the beach will gradually fill up with the excess water generated by the waves breaking on the sandbanks. The water level in the baïne is therefore higher than the ocean level, and the surplus will drain out to sea, giving rise to ” tourbillons ” causing strong currents pulling out to sea.  

When the tide is completely high, the water levels between the bay and the sandbanks are equal, so currents are very low or non-existent.
When the tide starts to go out again, the phenomenon of currents starts up again until the tide is completely out.

The strength of this bay current will vary according to the depth of the breach formed there, but also according to the strength of the waves and tides.
For example, the current will be much higher at ebb tide than at flood tide.

Most of the time, the current that carries the swimmers out to sea is faster than their swimming speed : swimming against the current to get back to shore therefore becomes impossible.

Diagram of a baïne

Image taken from the mini-documentary: “Swimming: How to deal with currents ?” ? – The best of Jamy’s world

How do you spot and protect yourself against baïnes ?

At low tide, you can easily spot the small pools of water. At high tide, if you see areas of calm water with no waves, surrounded by waves that break and break in the form of foam, then you’re dealing with a bay.

If the beach you are visiting has supervised swimming areas, we strongly advise you to swim there and to respect the areas marked with flags. And don’t hesitate to consult the information and recommendations for swimming put out by the lifeguard post.

We advise against swimming outside supervised areas. But in the absence of these, if you’re not sure where the safest swimming area is, don’t hesitate to ask surfers and locals for advice.

What can you do if you’re caught in a current of baïnes ?

If you are ever caught in a current, the first thing to do is not to panic and keep calm. As I said earlier, swimming against the current won’t do you any good, and will only exhaust you.
The risk of drowning is only increased if you exert yourself in vain.

The best thing to do is to let the current carry you along without exhausting yourself, so that nearby lifeguards or surfers can spot you and come to your aid.

You can also try to swim parallel to the current to get out of it and end up where the waves break over the sandbanks. You’ll be able to use the waves to get back to shore, or to help the lifeguards.

Whether you take part in water sports such as aquawalking or are just an occasional swimmer, it’s important to be aware of the baïnes phenomenon when you visit our coastal beaches. If you don’t already know how they work, it’s essential to inform those around you about the risks involved.

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