TG If you see square waves forming in the ocean, get out of the water immediately

There’s nothing more breathtaking than nature’s raw power and elegance. Just when you think you’ve seen it all, it unveils something extraordinary—like the mesmerizing phenomenon of cross seas, where waves form stunning square or grid-like patterns on the ocean’s surface.

At first glance, these watery checkerboards seem like a visual gift from nature. But don’t be fooled—their beauty hides a deadly truth.

Cross seas occur when two wave systems collide at angles greater than 45 degrees, or when wind-driven waves clash with ocean swells traveling in a different direction. The result? A powerful and unpredictable force beneath the surface that can endanger swimmers and even large vessels.

Despite their hypnotic charm, these square waves are notoriously difficult to navigate. According to a 2004 study cited by the European Space Agency, a significant number of ship accidents have happened under such crossing sea conditions.

One of the most well-known locations for this phenomenon is the Île de Ré, off the western coast of France. There, tourists can safely witness the spectacle from a lighthouse—because entering the water during a cross sea can be fatal.

So, the next time you see those perfect squares shimmering on the ocean, admire them from afar—and stay out of the water.

Watch the video below to learn more about this striking and dangerous phenomenon.