Once just legend, extreme rogue waves are a terrifying fact

For centuries sailors swapped terrifying stories of ships mysteriously vanishing, sunk by giant walls of water that seemed to appear from nowhere.

Some believe a rogue wave killed three lighthouse keepers who in 1900 disappeared from the Flannan Isles, a group of remote, rocky islands in Scotland’s Outer Hebrides.

When scheduled replacement lighthouse keeper Joseph Moore ventured ashore, he found the lighthouse empty, the clocks stopped and a half-eaten meal on the table.

Only a few rogue waves, defined by scientists as waves which are greater than twice the size of surrounding waves, have been observed directly.

But wave buoys have allowed scientists to document the ocean freaks, which strike fear into the heart of all seafarers.

“In some cases, there’s nobody left to tell the story,” Peter van Duyn, a master mariner, told 9news.com.au, speaking about the “certainty” of the existence of rogue waves, and the shift from fable to fact.

Van Duyn, a former captain of tankers and cargo ships, has encountered gigantic swells around the globe, from Cape Horn to the notorious Drake Passage near Antarctica.

The American woman died after she was hit by panes of falling glass which were smashed in as the ship was swamped by an unusually large wave.

“Normally a ship will just ride through everything,” Van Duyn said.

“The bow might disappear under a lot of water but slowly it does come up.

“That’s what you hope anyway, and it usually happens.”

“This glass can be pushed in by a massive wall of water.”

In the middle of raging seas, Van Duyn said it’s challenging for sailors to differentiate between a rogue wave and just a very big swell.

“From the ship, the bridge is usually quite high above the water, so to accurately measure wave height is quite difficult.

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“And it’s usually happening in a storm, so you’ve got other things to worry about.”

Rogue waves are unexpected, so a captain will have little warning and no time to change course or react.

Van Duyn was captaining a 300-metre-long, 300,000-tonne tanker off the southeast coast of South Africa, a passage notorious for “very big waves and troughs”, when his vessel was smashed by an immense wave and began to take on water.

“We don’t know whether it was a rogue wave or not,” he said.

“That particular area is known for it, rogue waves or very steep waves.”

From the ship’s bridge, a captain can see the bow of a long tanker actually bend as it crests over colossal beasts of the ocean, Van Duyn said.

“But if it flexes too much the hull can crack.”

The first rogue wave recorded, known as The Draupner Wave, was measured in 1995 off the coast of Norway at 25.6m, with surrounding waves approximately 12m.

That wave struck an oil drilling platform, and defied all previous scientific models.

In 2020, a rogue wave 17.6m tall was recorded off the coast of Vancouver Island, breaking the record for proportionality at three times the size of surrounding waves.

Scientists have also established that devastating rogue waves can sweep through the ocean, underneath the water’s surface.

“Internal rogue waves are cousins of surface waves – their shapes differ,” Dr Adrian Ankiewicz, from Australian National University, said at the time.

“They … move more slowly, at walking pace, and have much higher amplitudes, sometimes over 100 metres,” he said.