A study published in the journal Nature predicts that there are a half million cubic kilometers of fresh water beneath the seabed on continental shelves worldwide. The water is estimated to be low in salinity and potable.
The study’s authors reviewed seafloor water studies, comparing data sets collected during scientific missions, as well as those from oil and gas exploration. They found that freshwater below the seafloor is a common finding.
The deposits, researchers say, likely come from prehistoric rains that were absorbed into underground water tables when sea levels were much lower than they are today. As ocean levels have risen, the land and fresh groundwater beneath were confined under the sea.