Half of the Earth's living matter could be locked two to three kilometres below the ocean floor.
New Zealand co-ordinator for the Integrated Ocean Drilling Program, Guiseppe Cortese says the findings are thanks to IODP geosciences research programme.
For two months a crew of international scientists onboard the IODP's research vessel the JOIDES Resolution have studied the subsurface life in a largely unexplored region of the ocean between South America and Australia called the South Pacific Gyre.
In oceanography a gyre is a circular system of ocean currents.
"People are putting lots of effort into understand these things because it is completely new," Cortese said.
"Basically we didn't even know that this life existed and suddenly people are estimating now that more or less half of the biomass on earth is actually locked in these places."
The bacteria lives under very special conditions, he said.
"Some of them live with a very very small amount of organic matter, like energy sources or food, which means their metabolism is completely different from other life forms.
Understanding their metabolism could lead to the development of new medicines and technology.
The JOIDES Resolution arrives in Auckland today to exchange scientific teams.
On Wednesday it sets sail again - this time on a two month expedition that will see another team scientists drilling up to 350m below the sea floor to collect samples of four extinct volcanoes that form part of the 4300 km underwater Louisville Seamount Trail volcanic chain.
By drilling into the seamounts off the northeast coast of New Zealand scientists hope to examine the trail's eruptive cycle, geochemical evolution and whether or not the Louisville hotspot has moved.
Cortese said while the scientists will be looking forward to setting off, the work is "very very very tiring".
"Essentially people work on 12 hour shifts - you go to sleep, maybe relax one hour or two hours, when you wake up you already have work lined up for you.
"The drilling operation goes 24/7 - so there is no respite in a way."
One of those shifts will include whale watch.
"These ships, in order to find what is below the sea floor, they have instrumentation that uses sonar," Cortese says.
"For some people, they think that this is a hazard to the health of whales and dolphins and so on.
"But there are rules. All of these ships, when they go on expedition, are required to have part of their crew looking out for whales.
"So if the sonar is on and suddenly somebody sees a whale all the operations stop because they don't want to endanger their health."
On Wednesday leaders from both expeditions will give a public talk at the Auckland Museum.
Visitors can also follow the progress of the Louisville expedition through an interactive exhibit in the Museum's ocean gallery.
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