What are Square Waves and Why You Should Stay Away from Them

We all love spending summers at the beach, enjoying the water and soaking up the sun. But it’s important to always be cautious and aware of potential dangers, like square waves in the ocean. While they may look fascinating, square waves are actually one of the most dangerous things you can encounter in the water.

Here’s What To Do If You See Square Waves Forming In The Ocean

Understanding Square Waves

Square waves, also known as cross seas, occur when two or more swells meet and form a square pattern that resembles a checkerboard. They are quite common in the ocean, happening when a windsea and a swell, or two swell systems, coexist. These unique conditions make square waves a hazard for boaters and swimmers alike.

The Dangers of Square Waves

Cross seas can create swells that reach heights of up to 10 feet, causing unpredictable and challenging wave patterns. Navigating through these treacherous waters can be extremely difficult for boaters, and even swimming becomes risky. If you happen to come across square waves, it is best to avoid going out on a boat or swimming in the ocean. Instead, relax on the beach and wait for better conditions to venture out into the water.

Where to Find Square Waves

Square waves are most commonly found at the junction of two oceans or large water bodies, such as peninsulas. These unique wave patterns can be observed in places like the Isle of Re in France, located off the coast of La Rochelle. Another notable location is Cape Reinga in New Zealand, where the Tasman Sea and the Pacific Ocean collide.

While these places attract tourists with their stunning square wave displays, it is crucial to observe them from a safe distance. Although it may seem intriguing, it is best to stay away from these intersecting waves in order to ensure your safety.

The Science Behind Square Waves

Interestingly, square waves can also be seen in shallow waters off the Isle of Rhe and Tel Aviv, Israel. Scientists attribute the formation of square waves to the Kadomstev-Petviashvili equation, which describes nonlinear wave motion. This equation helps explain how different weather systems interact with each other.

Remember, if you spot square waves, admire them from a safe distance and avoid entering the water. Your safety should always be the top priority.


  • “Square Waves Are a Thing — and If You See Them, Get Out of the Water Immediately.” Travel and Leisure. Stacey Leasca. June 7, 2023.
  • “Square Sea Waves: What They Are & Why They Occur.” House of Surf. September 27.
  • “Square Waves in Ocean Settings Are Rare But Dangerous.” How Stuff Works. John Perritano. October 23, 2023.

Watch this short video to learn more about square waves: