Square Waves: What They Are and What They Mean

Seeing some square waves? Run for safety ASAP.

You’re used to the undulating shape of a wave as it approaches the shore, like several connected semi-circles. You see waves that meet like cross-hatches and think it’s fascinatingly unusual. 

It’s bewitching, it’s impressive, but like the sirens that inhabit the ocean, it’s dangerous. Never swim when you see square waves; if you’re already in the water, run for the shore immediately.

But why? Square waves, though rare, are one of the most dangerous things to happen in the ocean for swimmers. Even seasoned ones are known to drown in such waters.

What makes these waves fatal? What’s the best way to avoid being caught in them? This blog post helps answer these questions and more.

What are square waves?

In its simplest definition, square waves happen when two ocean swells from opposite directions meet together.

Remember, ocean swells are a series of waves formed along by winds blowing in the ocean.

These two swells meeting together create the characteristic grid-like appearance. Ocean swells can be pretty powerful, and when two meet together, they can easily swamp swimmers or even a small boat.  

Because the waves come from multiple directions, it’s difficult for a swimmer or a boat to maneuver in such conditions. 

The dangers of square waves for a swimmer

One of the best strategies to survive rough waves is to swim under the waves and try to body-surf your way to the shore.

However, with square waves, this will be more challenging since two swells will pull you in different directions. Moreover, square waves often generate rip currents, dragging a swimmer farther from the shore.

Since rip currents are fast and powerful, they can be hard to navigate and can exhaust even a seasoned swimmer.

Square waves and seacraft

Being on a boat or a ship does not protect one from square waves, though.

Square waves in shallow waters near the shore pose a little less danger to swimmers than ships in the open seas. 

The opposing motions in the ocean brought about by these kinds of waves can easily make a ship keel over and lose control.

Some ships follow the wave’s direction instead of opposing it. The vessel is torn in two directions when two forces act on the boat.

It takes a good captain with superb ship-handling skills (as well as a vessel in good condition) to survive rip currents and other ocean turbulence brought about by square waves.

Surviving square waves as a swimmer

So the inevitable happens; you’re swimming, and suddenly, someone alerts you about square waves. Here’s what you can do:

Don’t get in

Save yourself from danger, and don’t swim in the water. Even if you’re in the shallows, square waves can overwhelm you. Inexperienced swimmers are more likely to get confused during unusual sea phenomena and may panic, resulting in drowning.

Get out of the water

Rush to the shore as soon as you can. Square waves are highly unpredictable. They can last for a minute or two, dissipate at times, or generate powerful rip currents that can take you deeper into the ocean.

Control your breathing

This practice is true for all swimmers. Breathing control can make or break you when it comes to water-related disasters. The more you control your breathing to prevent inhaling/drinking large amounts of water, the better your chances of survival.

Swim along with the current, not against it

This tip will become more challenging as you deal with one or two swells. However, you will notice that one swell is stronger than the other. Swim along with the stronger one until the square waves stop.

Once the square waves return to normal, swim to the shore quickly.

Surviving square waves in a boat or ship

In the open ocean, boats and ships risk capsizing when encountering the massive energy of more giant square waves. 

If you’re an avid sea explorer on a small boat, always check the area to see if square waves are likely to happen there. Otherwise, avoid boating in unfamiliar places.

When you are on a ship, it’s unlikely that you will know if the turbulence is caused by cross waves, rip currents, or simply bad weather. Strap on your life jacket and follow the instructions of the ship’s staff.

When the ship seems to be sinking, secure a lifeboat. Don't flap around and make unnecessary movements when you’re in the water (ideally with your life jacket). Get in the lifeboat and limit yourself from thrashing.

FAQs about square waves

Are square waves a sign of underwater earthquakes?

No. Underwater earthquakes do not produce square waves. They instead lead to tsunamis.

Do square waves happen regularly everywhere, or is it rare?

Generally, square waves occur only when two swells meet and clash against each other, which is rare. However, the Isle of Re in France regularly gets square waves due to its location- this is where the Gulf Stream’s warm waters meet with the cold currents of the Atlantic Ocean.

Are square waves enough to cause shipwrecks?

In the open sea, yes. Square waves can reach up to 10 meters in height, enough to throw a ship off balance. The rolling motion of the two clashing swells can cause water to get inside a vessel and result in capsizing.

How serious is a square wave for surfers and swimmers?

Quite serious. More often than not, square waves indicate reasonably strong rip currents. These currents sweep swimmers and surfers into deeper waters where swimming may be more challenging. Inexperienced swimmers may need help returning to the shoreline after being caught in a rip current generated by square waves.

What places in the world can we regularly observe square waves?

Aside from Ile de Re in France, Newport Beach’s Wedge in California and some offshore areas in Hawaii experience square waves when the conditions are right.

Waving Away from Square Waves

All in all, square waves threaten swimmers, surfers, and sea vessels. It is best to stay away from places where these regularly occur. Keeping a watchful eye on sea conditions when venturing out in the sea is still the best way to avoid harm from these waves.

Oliver Jones

Written by Oliver Jones

I'm a dedicated surfer and writer, and my heart truly belongs to the ocean. Surfing is not just a sport but a way of life for me. I ride the waves in the water and on paper, pouring my passion into every word I write.

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