Square Waves

When you say square wave, it sounds as if it belongs to the realm of advanced physics or synthesizer music and has nothing to do with surfing. While that’s not completely untrue, sometimes these ocean waves we hold so dearly can form squares as well, and that’s quite a strange sight to see.

If you want to see these square waves, you can visit Île de Ré, a French island on the Atlantic Coast of the country, as it’s the location where this rarest of wave systems occurs most commonly. Once you're a safe distance from the sea, you’ll see that the waves form a shape like a chessboard.

And, of course, you’ll probably ask yourself: What is this new devilry? What on Earth or in Hell might be causing this? Is it possible to swim in such waters? Is it possible to surf on such waves?

Well, let us answer those questions.

How Do Square Waves Occur?

Square waves are sometimes also called cross-sea waves, cross waves, or simply cross-seas. While the names don’t really convey their definition and causes to the fullest, they’re not completely off the mark. Square waves occur when waves that have different angles and are from two separate weather systems collide and form wave blocks.

As waves in the open ocean mostly move in the same direction, unless there are crazy storms, it’s quite a strange and rare phenomenon as well. That’s also why Île de Ré, an island located at the intersection of two seas, is the place where you can see square waves in their full glory.

However, we should also say that, as you might have observed for yourself during the last couple of years, the weather systems are now getting more and more unpredictable. That causes stranger patterns for the wind, and when the wind gets strange, it’s possible to have two wave directions at once since the wind plays an important role in how waves are formed.

So, if the unpredictability of the weather is any indication, we’ll get to see more and more square waves going forward. And although they make a strange yet beautiful sight to see, these cross-seas aren’t exactly innocent.

Why, you’re asking? Let’s find out.

Are Square Waves Dangerous?

We’re talking about battling waves from two different weather systems moving in opposite directions with their arms out. Of course, they’re dangerous; they’re even so extremely dangerous that, should you see them, you should get out of the water immediately.

When these waves moving in different directions meet under that good-looking, chess-board-like grid system, it means that there are rip currents going on underneath. Rip currents by themselves are, as you know, one of the most fearsome natural threats for surfers and swimmers alike. Rip currents beneath cross-sea waves are even more powerful and dangerous than your regular rip currents.

Therefore, even though the square waves can be a great tourist attraction, it’s also good to know that they’ve so far caused shipwrecks and many boating accidents. If they present enough of a danger for ships and boats, it’s only logical to assume swimming or surfing in these waves would definitely be life-threatening.

Moreover, you can escape rip currents by swimming parallel to the shore, but that’s not an option for cross-sea waves since navigating through their grid system is nearly impossible.

Wrapping Up…

Well, no matter how skillful and confident a surfer you are, safety should always come first. So, whenever you see square waves, get out of the water ASAP! That being said, they’re really a sight to see, and if you want to see some, you have a couple of other options besides the already-mentioned French island: Portugal and New Zealand.

In addition, don’t forget to check out our other guides on how to improve your Ocean IQ. Moreover, we have two programs that’ll endow you with all the wave knowledge you need: Surf Science and Waterman.