A buoy measuring waves in the tumultuous Southern Ocean has broken free and is heading to Chile.

The Southern Ocean Buoy, pivotal in a collaborative research project between the Defence Technology Agency and MetOcean Solutions measuring subantarctic wave conditions, has snapped its moorings and is drifting east across the Pacific.

It could take more than a year before it arrives at its unscheduled South American destination.

Up until last month the scientific buoy was stationed south of Campbell Island relaying wave data through a satellite link for the last six months.

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But on July 28 the buoy suddenly started drifting east with the ocean currents and has continued to head across the ocean on course for South America.

"We're not exactly sure what happened," said MetOcean's managing director Dr Peter McComb. "However it's likely the compliant bungy section of the mooring failed under the extreme wave conditions down there."

McComb said the maximum waves heights had exceeded 10m for more than a quarter of time with the mooring facing constant stresses and ferocious storms.

"Since February 2017, the maximum wave heights have exceeded 10m for 26 per cent of the time, and there are very few places on our planet that energetic.

"At the start of the project there were many uncertainties. Would there be enough solar power to keep it alive during the deep south winter? Would the mooring survive the constant stresses and ride out the ferocious storms?

"Ultimately, we are very pleased to have succeeded in our goal of making almost six months of very detailed spectral measurements at this location in the subantarctic."

He said the fact that the buoy continued to relay information meant an unexpected spinoff for researchers.

"Another positive outcome is the realisation that our research project is not over yet - the buoy continues to measure wave spectra and send its data via the satellite link as long as there is sufficient solar power.

"Now we have a new and unique opportunity to make ongoing Southern Ocean wave measurements at the very extremity of the planet's largest ocean - the Pacific. It's highly valuable data for oceanographers."

He said it may take more than a year for the buoy to reach Chile and so long as there was sufficient sunlight it would provide significant additional data.

The data already collected will be used for a number of civilian and military applications including helping the New Zealand Defence Force design its next class of patrol ships suited to the harsh Southern Ocean climate and developing a global wave model.

A second wave buoy off will be moored off Campbell Island next February.