What Are Square Waves in the Ocean?

Have you ever seen a strange sight of square patterns in the ocean while swimming, surfing, or hanging out on the beach? If so, you’ve witnessed square waves in the ocean. This is also called cross sea, and while it looks cool, it’s actually pretty dangerous.

What Are Square Waves in the Ocean?

While this rare wave pattern is risky, it’s easy to notice. Being aware of what’s happening when you see cross seas can help you stay safe at the beach. Keep reading to learn more!

What Causes Square Waves in the Ocean?

While square waves appear to be caused by something underwater, that’s actually not the case. In fact, they occur when two wave systems meet.

Typically, waves come in and crash parallel to the shore. These waves are caused by wind rippling the surface of the water.

When there’s no wind to interrupt swells, waves continue to travel into the open ocean. Sometimes the direction of the wind changes, and this also affects wave patterns.

When we’re dealing with two waves systems, eventually two opposing swells collide. This is when a cross swell occurs, creating square waves.

Why are Square Waves Dangerous?

Watching square waves might seem fascinating, but it’s essential to understand that they can be extremely dangerous. This is because the two wave directions are more powerful than rip tides. With that said, if you think there’s a possibility you’re witnessing two weather systems forming square waves, it’s time to head to shore immediately.

If you’ve ever stood on the shore and tried to wade through rolling breakers or tried to paddle through the surf on a surfboard, you know how strong typical waves can be as they work toward the shoreline. 

Below the surface, the sea currents move toward one another at an angle, sometimes greater than 45 degrees. Their collective energy is incredibly powerful when you’re dealing with battling waves. Studies have shown that this strength does cause boating accidents, drownings, and other dangers in the water.

Not-so-fun fact: Cross seas can result in waves up to 10 feet high!

Square waves in the ocean happen when two opposing swells collide.
Square waves in the ocean happen when two opposing swells collide. (Credit: LetsGetPhil/Shutterstock)

Other FAQs About Square Waves

If you’re just learning about square, or cross, waves, you probably have a few more questions. And, we’re here to answer those for you! The more you know about ocean dangers, the more careful you can be so that you can enjoy your time at the beach.

Are square waves and a cross sea the same?

Yes, ‘square waves’ and ‘cross sea’ are used interchangeably. Square-patterned waves create a cross pattern on the surface of the water. These terms are both used to describe what happens where two separate weather systems collide and create this unique wave pattern.

Are riptides the same as a cross wave?

Riptides are similar to square waves in that they can be extremely dangerous for swimmers, surfers, etc. But, that’s about the extent of what they have in common.

Riptides pull water out into the sea, usually resulting from a storm offshore. On the other hand, square-patterned waves result from changing winds that cause older waves to continue as opposed to breaking at shore.

Where do square waves happen?

The good news about these harmful waves is that they don’t happen at most beaches. That said, you’re probably safe to visit your favorite beach!

While you can see square waves at various beaches with shallow waters, the weather and ocean pattern in some areas of the world is more conducive to forming these waves. One famous place where cross sea often happens is the Isle of Rhé. This island is on the west coast of France, and a nearby lighthouse is a popular tourist attraction where visitors watch cross sea from above.

Other places you might see cross waves include the Isle of Re in France, the shores of Lisbon, Portugal, and beaches near Tel Aviv, Israel.

Final Thoughts

If you ever witness waves moving and forming this unique pattern, it’s safe to say you’ll be intrigued. But, remember that the power they can produce is dangerous to those in the water. As with any time you visit the beach, be mindful of the conditions, head to shore if you need to, and you should be good to go!

You May Also Like