Rogue Wave: How They Form and Where They Occur Most Often

Written by Kristen Holder
Published: June 13, 2023
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Rogue waves are an integral part of folklore around the world. Cruise ships have lost eleventh-story windows to rogue waves over 70 feet tall. Curious to learn more about a rogue wave? How they form and where they occur most often is coming right up.

What is a Rogue Wave?

Rogue waves are solitary and might move in a different direction than surrounding waves.

Rogue waves are solitary and might move in a different direction than surrounding waves.

©AlexLinck/Shutterstock.com

A rogue wave is a solitary wave on the open ocean that is at least twice as big as the largest of the surrounding waves. It sometimes travels in different directions than the direction of the waves near it. These alarmingly large waves are important to humans because their unpredictability makes them unavoidable.

Rogue waves are the large and unexpected waves on the open ocean. These waves occur in both stormy seas and on calm days. That’s because their creation is dependent on shallow water currents, which interact with even the smallest ocean swells.

If conditions are right, rogue waves develop anywhere. However, they are not the same as the irregular waves seen near shores, as these beach waves are caused by different things. The sparse yet large waves that come to shore are called sneaker waves. 

Rogue waves are also not tsunamis. They are not caused by deep water displacement, nor do they last for long periods. They also do not travel large distances as they’re dependent on localized surface conditions.

How Does a Rogue Wave Form?

Spinning eddies moving opposite of established currents sometimes create rogue waves.

Spinning eddies moving opposite of established currents sometimes create rogue waves.

©Doug McLean/Shutterstock.com

No one knows why rogue waves are created, but there are a few theories. These theories relate to the energy stored in water movement in the planet’s oceans.

One idea builds on the energy offered by established and constant ocean currents. When a swell and an ocean current interact with each other in just the right way, a single swell may become much taller and thinner than normal. These enhanced swells are devastating if they’re large enough because they become monster rogue waves.

Another theory calls to light the importance of chaotic water movements in the oceans. Eddies are formed in the open ocean along currents. They are independent currents of water outside defined currents with separated energy.

These eddies spin in opposite directions as normal currents, and sometimes swells are caught up in them. If conditions are just right, large eddies create rogue waves. Since eddies sometimes exist randomly in the open ocean, the potential for a rogue wave is possible at any time.

Some scientists think that large waves which meet at a big angle above 60 degrees may sometimes behave dramatically. Sometimes, cresting waves in this situation have one wave break over the top of another that is breaking in front of it. If this occurs in a particular way, both breaking waves combine to create a large momentary height increase seen as a rogue wave.

Where Do Rogue Waves Occur Most Often?

Reef shark headbutts diver

In 2018, 3 tourists in South

Africa

died after a rogue wave capsized their shark diving boat.

©Andrea Izzotti/Shutterstock.com

Rogue waves occur most often near South Africa’s southeast coast. However, they occur at a higher rate than average anywhere in South Africa. The Agulhas Current, the second fastest ocean current in the world, makes a wide hairpin turn back into the Indian Ocean that it came from at the southern tip of Africa.

This bending current interacts with swells created by weather in unique ways that are sometimes destructive. Because the current and weather conditions coincide in just the right way, the frequency of rogue waves in this region is dramatically higher than in other parts of the world.

Tourists engaging in a shark diving expedition near Gansbaai in South Africa became victims of a rogue wave on April 14, 2008. The expedition boat capsized, and three people died.

Even though it seems like rogue waves only appear in oceans, that isn’t true. There are reports of rogue waves on Lake Superior in North America. This may be due to the extreme weather and fast currents present in North America’s largest lake.

The largest rogue wave ever recorded happened in November 2020 in the North Pacific Ocean. It was so big that scientists guess that a wave this size will not be seen for another 1300 years.

This North Pacific rogue wave isn’t the tallest recorded rogue wave at 58 feet. However, it was more than three times the size of the largest waves around it.

This kind of increase in size has frightening implications for events like this. Future scenarios may mimic this but contain more force and more water. Rogue waves larger than any recorded naturally is a mathematical possibility.

Are Rogue Waves Dangerous?

Large deep sea fishing boat scene from the bridge of the boat large wave hitting the bow of the boat

Rogue waves that are not hit straight on can easily capsize large ships.

©Elmer Laahne PHOTOGRAPHY/Shutterstock.com

Yes, rogue waves are dangerous. They wreak so much havoc on humans that there are ancient stories describing them. They’ve haunted sailor accounts in written records for centuries. Today, their existence, along with the threat they bring, is considered fact instead of fable.

They are unpredictable, which makes them very menacing. They’re so strong that large ships sometimes experience cracked hulls due to these big waves. These cracks sometimes escalate into hull failures which may be the fate of some ships lost to the sea

Since rogue waves appear quickly and are short-lived, there is little to no warning of their approach. As a result, boat captains sometimes aren’t able to steer their vessels into the wave properly.

If a rogue wave hits a ship from the side instead of straight on, it may capsize the ship. Even huge ships with heavy loads, like cargo ships, are easily capsized by the largest rogue waves that directly hit the starboard or port.

How to Best Avoid Rogue Waves

Even though calm water means there is less of a potential for a rogue wave, the possibility is always there

Even though calm water means there is less of a potential for a rogue wave, the possibility is always there.

©ganjalex/Shutterstock.com

While it’s never possible to eliminate the danger of encountering a rogue wave, some considerations can be made with safety in mind. While rogue waves do occur on clear days, the chances of one developing in calm waters are lower than during a storm. This is because there isn’t much energy sloshing around in the form of surface water agitation.

Keeping away from strong currents is also another way to avoid rogue waves. Monster waves are often caused by outside factors interacting with huge swaths of quick directional water movement. If there are strong winds in the forecast, traversing into the deep sea may come with higher dangers of rogue wave encounters.

The photo featured at the top of this post is © AlexLinck/Shutterstock.com


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About the Author

Kristen Holder is a writer at A-Z Animals primarily covering topics related to history, travel, pets, and obscure scientific issues. Kristen has been writing professionally for 3 years, and she holds a Bachelor's Degree from the University of California, Riverside, which she obtained in 2009. After living in California, Washington, and Arizona, she is now a permanent resident of Iowa. Kristen loves to dote on her 3 cats, and she spends her free time coming up with adventures that allow her to explore her new home.

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