International researchers are coming together to investigate a powerful force that lurks hundreds of metres deep in the Tasman Sea.

But there are no jaws, teeth or tentacles involved.

It's known as a sub-surface wave, and its impact on the global climate and marine ecosystem is significant, Hobart-based biological oceanographer Peter Strutton says.

"The waves that happen deep in the ocean can be really large: 100 metres or more," the University of Tasmania associate professor said.

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"And the middle of the Tasman Sea is a global hot-spot with its strong tides and ridge along the sea floor, like a mountain ridge."

It means that in the waters between New Zealand and Tasmania, waves gather strength during a journey lasting about four days and covering 1400km before slamming into a shelf off the island state's east coast.

Dr Strutton will be one of more than 60 scientists on two ships monitoring the waves and where the energy goes once they break.

"We will run a line from the bottom to the surface and measure things like water density and salinity as it passes," he said.

"This study is going to help us understand how these internal waves bring nutrients from the ocean floor and stimulate activity by providing food for plankton."

The measurements will also provide a better understanding of how cold water from the depths comes to the surface in an essential ecological mixing process that moderates oceanic water temperature and takes carbon dioxide out of the atmosphere.

Sub-surface waves exist across the globe and researchers from five Australian universities are involved in the study, as well as others from the United States.

The first of two US vessels, the Roger Revelle and Falkor, will leave Hobart tomorrow to begin the research.

- AAP