Experts Warn If You Ever Notice This Strange Sign in the Ocean — You Should Get Out ASAP

To witness a train of waves rolling and crashing in the ocean is nothing less than magic. The science behind the formation of these waves lies in the movement of winds, per NOAA. When spirals of wind sweep over the ocean and brush its surface, they transmit intense energy into the water, disturbing its stillness and prompting the formation of waves that range from gentle ripples to colossal high tides. When these waves lap the shoreline, spilling onshore on wet patches of shifting sands, they evoke an aura of surreal tranquillity.  

In some instances, however, these waves can take the form of freakish geometrical monsters that can swallow up the surfers. Boats and ships will rock violently, eventually tumbling down into the belly of the ocean. Called “square waves,” they appear as if dividing the surface water in a bizarre pattern of squares. While the thought of a “square wave” might sound even more fascinating than a regular circular wave, these squares are downright treacherous, as much as those vigorous rip tides and shark attacks. When the surface becomes a trellis of these square waves, experts suggest it’s better to stick to the shallows.

"If caught in a square wave, the most important thing to do is get out of the water immediately, as they are extremely dangerous. Stay calm, try to float on your back, and swim parallel to the shore to escape the wave's force. Then carefully make your way back to land as soon as possible; if you can't reach the shore quickly, signal for help,” Mathew Giachetti, of the United States Lifesaving Association (USLA), told Islands.com. Also called “cross sea waves,” square waves are usually formed when two weather systems or swells traveling in alternate directions collide with each other at right angles. 

Guided by crisscrossing winds, these two wave systems traveling at different speeds cross each other’s paths, emblazoning the ocean surface with a rare sighting that can look like a pattern of quadrilaterals, checkerboards or chessboards. A square wave can tower as high as 10 feet, according to Travel & Leisure Magazine. What makes these waves so dangerous is their powerful rip currents that can make surfers, boats, and vessels lose their balance and capsize. Even larger ships struggle to hold their stability amidst these waves. 

IFL Science explains that there could be several reasons behind the formation of these grid patterns, but mostly, it happens when the weather pushes waves in one direction while the currents move in another. Tropical storms or wind shears can also redirect waves in opposite directions, causing a collision. Reports suggest that these square waves have caused massive destruction to people and vessels in the past. For instance, SurferToday describes that these square waves were responsible for many ship accidents and shipwrecks from 1995 to 1999, as shared by the European Space Agency (ESA).

Historical records also include the case of the German research icebreaker vessel, RV Polarstern, which was one of the first few vessels to document these hazardous waves. According to The Guardian, various studies have found that a disproportionate number of accidents happen in waters experiencing square waves, so evidently, they’re something to avoid in the open ocean.

These notorious geometrical wave patterns are rare, but they are observed worldwide in many places. Take the Isle of Rhé in France, an infamous location that attracts thousands of tourists eager to witness the rare spectacle by clambering up on the lighthouse. They have also been recorded off New Zealand's Whangamatā Beach, Anna Maria Island, Florida, and in Turkey’s Aegean Sea, where recent sightings have drawn much attention. SurferToday also spotted them in Helsinki's Mustikkamaa island in Finland.