A 19.4m wave has been detected south of New Zealand - and the company that recorded the behemoth believes monsters reaching over 20m were probably created by the same storm.

In a collaboration with the New Zealand Defence Force, science-based consultancy MetOcean Solutions recently moored the high-tech instrument in the Southern Ocean off Campbell Island, nearly halfway between the South Island and Antarctica.

Persistent westerly winds and an unlimited area for waves to build combine to make Southern Ocean waves among the biggest in the world.

Yesterday, MetOcean Solutions confirmed it had picked up a 19.4m wave - close to the highest wave ever recorded, which was detected rolling through the North Atlantic Ocean between Iceland and the UK last year.

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It's expected the buoy may be ultimately register waves 25m high - the height of an eight-storey building - as it continues its real-time readings fixed in 150m of water.

But MetOcean Solutions senior oceanographer Dr Tom Durrant was nonetheless thrilled with Saturday's detection.

"This is one of the largest waves recorded in the Southern Hemisphere," he said.

"This is the world's southernmost wave buoy moored in the open ocean, and we are excited to put it to the test in large seas."

The company's managing director, Peter McComb, told the Herald that waves larger than 20m likely also occurred between the sampling times, which took place for 20 minutes every three hours.

Sub-Antarctic waters were difficult to work in, and reliable wave data for the area is scarce.

Improved observations would enable better forecasting and design of vessels built to withstand Southern Ocean conditions.

"The buoy is performing extremely well so far," Durrant said.

In a collaboration with the New Zealand Defence Force, science-based consultancy Metocean Solutions recently moored the high-tech instrument in the Southern Ocean off Campbell Island, nearly halfway between the South Island and Antarctica. Photo / MetOcean Solutions
In a collaboration with the New Zealand Defence Force, science-based consultancy Metocean Solutions recently moored the high-tech instrument in the Southern Ocean off Campbell Island, nearly halfway between the South Island and Antarctica. Photo / MetOcean Solutions

"Not only is it surviving these large waves, but it is making detailed recordings of extreme sea states in the Southern Ocean, a region rarely observed by in-situ instruments."

During the depths of winter, Southern Ocean waves are enormous, with significant wave heights averaging more than 5m, and regularly exceeding 10m.

Individual waves could double that size.

Image / MetOcean Solutions
Image / MetOcean Solutions

Accurate measurements of these conditions will help researchers understand waves and air-sea interactions in these extreme conditions.

This in turn would lead to improvements in the models used to simulate the waves, providing better forecasts, both for the Southern Ocean and for the wider region.

"Waves generated in the Southern Ocean have far-reaching effects, contributing significantly to the wave climate in all the major ocean basins," Durrant said.

There are separate plans for a multi-million dollar research station on Sub-Antarctic Auckland Island, which would allow scientists to study deep-sea currents in latitudes where projected changes in climate are expected to be seen most rapidly.

The Southern Ocean Wave Buoy data are freely available from MetOcean Solutions and can viewed here.