Takeaways from a hunt for 'secret' fresh water under the North Atlantic seabed

ABOARD LIFTBOAT ROBERT, North Atlantic — It turns out the Continental Shelf has been holding a secret from the ages. Beneath the sea floor off the U.S. northeast lies an enormous reserve of fresh water whose existence was long unknown, then was suspected and now is confirmed.

The first global expedition to drill systematically for undersea fresh water has come away with thousands of samples of it. And this comes as rising sea levels and other harms from a warming climate threaten freshwater supplies on land.

Expedition 501, a $25 million collaboration of more than a dozen countries including the U.S., drilled 20 to 30 miles (30 to 50 kilometers) off the coast into what is now believed to be a freshwater reserve stretching from New Jersey to Maine. It's just one of many prospective deposi