Scientists discover huge freshwater aquifer below the Atlantic Ocean

Scientists have identified signs of a huge aquifer off the US coast. Photo / Supplied

Hidden off the coast of the US is an invaluable treasure — which could be a boon with the world's population set to spike.

Scientists investigating off the coast of New Jersey have made a stunning discovery — enough freshwater to fill 1 billion swimming pools buried underneath the ocean.

It's believed to be the biggest known undersea freshwater aquifer on Earth.

A study published by nature reveals the huge aquifer contains at least 2,800 cubic km of mostly freshwater.

The team believes groundwater contained within continental shelves is a global phenomenon.

That could have implications across the world as population growth surges.

The UN estimates there will be 9.7 billion people living on Earth by 2050.

Countries including India are already suffering major shortages — with Chennai already running dry.

At least 21 cities in India are expected to run out of groundwater by 2020, with 100 million people to be affected.

Trucks have brought in water for residents in Chennai, with wealthier citizens hiring their own tankers. Photo / AP

Researchers from Columbia University and the Woods Hole Oceanographic Institution made the find while surveying the ocean floor off the northeast coast of the US.

The researchers measured electromagnetic waves to map the water, which remained invisible to other technologies.

"We knew there was freshwater down there in isolated places, but we did not know the extent or geometry," lead author Chloe Gustafson said, a PhD candidate at Columbia University's Lamont-Doherty Earth Observatory.

"It could turn out to be an important resource in other parts of the world."

Scientists have identified signs of a huge aquifer off the US coast. Photo / Supplied

It's believed the water in the aquifer is from ice that melted after the last ice age 15,000 to 20,000 years ago.

It was then trapped in rock

It's possible the aquifer is also being fed by run-off from the land.

The aquifer spans at least 350 km of the US Atlantic coast.