Researchers from Columbia University and the Woods Hole Oceanographic Institution have discovered a massive freshwater aquifer in the Atlantic Ocean, from New Jersey to Massachusetts.
The discovery was made while they were doing a survey of the sea floor off the US northeast coast.
It contains at least 2,800 cubic kilometers of liquid.
It's the biggest known undersea, freshwater aquifer on Earth.
The freshwater aquifer likely formed after the last ice age.