If you search for "square waves" on Google, you will be met with some pictures of a very strange chessboard wave pattern and videos with clickbait titles like, "If you see these waves: GET OUT OF THE WATER".
So, what's going on here, how are these oddly-shaped waves formed, are they really dangerous and if so, why?
What are Square Waves?
Square waves are formed when varying weather systems converge at different angles.
The phenomenon is seen in areas where different seas meet, and it is very rare.
Simply put, the sea creates different wave systems, and these combine to create the effect of square waves.
Are Square Waves Dangerous?
If you have seen any pictures of square wave patterns, also known as "cross waves", it's probably one that depicts a chessboard sea with a lighthouse in the foreground.
The picture was snapped at Île de Ré, which is near La Rochelle in France. As weird as it looks, it's genuine, but the warnings that depict square waves as possessing some kind of Cthulhu-esque power, are definitely not.
At least not in the way shown by this image.
There are certainly studies that suggest cross seas cause more boating accidents, as it seems that the converging waves combine to rock and roll the boats while allowing more water to get on board.
However, there is no suggestion that such accidents are greater when square waves occur close to the shore, as seen in the famous image.
The rip currents can be stronger, though, and to be on the safe side, you may want to stay onshore. But there should be no immediate or sizeable risk to surfers or swimmers.
Where Can You See Square Waves?
As noted above, the island of Île de Ré in France is one of the best places to see these waves in action.
There are numerous pictures and videos out there that have been taken from this location.
They do appear elsewhere, as well, but they are very rare, and they typically don't last for more than a few minutes.
By the time you realize that the phenomenon is happening, and you rush to grab your drone or even dig out your iPhone, it may already be over.
Then again, that's why YouTube exists, and if you want to investigate these waves some more, you're always just a quick search away!
Unfortunately, however, most videos showcasing these waves also come with skull & crossbones and exaggerated warnings.