A massive freshwater aquifer has been discovered beneath the Atlantic Ocean, off the northeastern coast of the United States.

But scientists are not surprised of this latest discovery. According to Science Alert, in the 1970s, researchers had seen the signs of freshwater in the Atlantic Ocean. Live  Science said companies drilling off the coast for oil had struck freshwater.

“Oil companies had occassionally discovered freshwater when drilling for fossil fuel, so scientists were aware that something is down there,” said Science Alert. However, they had no idea what lay beneath - a huge resevoir trapped in porous rock, which may stretch from Massachusetts to southern New Jersey, about 220 miles.

Researchers believe fresh water may have gotten trapped under the Atlantic Ocean during the Ice Age about 15,000 to 20,000 years ago. They explained the world’s water was locked up in glaciers. Live Science said large pockets of fresh water from the melted glaciers got stuck in the sediment traps; sea levels later rose and as a result fresh water and sediments got trapped under the ocean.

A marine geologist from Columbia University, Chloe Gustafson said they knew about freshwater in isolated places. However, she said they did not know the extent.

The study, which was published in Scientific Reports, said a continuous submarine aquifer system spans about 350 kilometers of the US Atlantic Coast and contains about 2800 cubic kilometers of low-salinity ground water. Furthermore, it says that the findings can be used to improve models of past glacial, eustatic, tectonic and geomorphic processes on continental shelves. 

The team of resarchers used various models and methods such as marine electromagnetic (EM) and paleo-hydrologic modeling to determine the freshwater reservoir. Live Science said the researchers dropped instruments to the seafloor to measure the electromagnetic fields. The researchers said salt water conducts electromagnetic waves better than fresh water does, thus any pools of fresh water would stand out as bands of low conductance.

They found freshwater to be continuous, starting from the shoreline and extending out to the continental shelf. “It also ran deep starting at about 600 feet below the ocean’s floor and ending at about 1,200 feet below the seafloor,” said the study.