Guest Column: Fresh water… below the ocean?

Fresh water… below the ocean?

by Kayla Glynn

The need for fresh water is growing. Sea level rise is threatening coastal fresh water sources, pollution is rampant, and climate change is causing impacts to the natural hydrological cycle. By 2030, the United Nations believes that the global demand for fresh water will exceed supplies by 40% (Jaynes, 2023). Feeling threatened by this timeline, researchers have started to look for new sources of fresh water, including in some of the last places you would think to search. 

Surprisingly, there are many potential fresh water depositories underlying shallow ocean waters around the world. One of which is located off the coast of the northeastern United States (Woodward et al, 2025). About fifty years ago, a US government ship was searching for minerals and hydrocarbons off the East Coast by drilling into the seafloor, but instead found fresh water. It wasn’t until 2015 that a team from the Woods Hole Oceanographic Institution and Lamont-Doherty Earth Observatory used that discovery to map an aquifer, and roughly estimate the waters’ salinity using electromagnetic technology (Krajick, 2019). This groundbreaking research allowed them to report evidence of a “massive offshore aquifer system”, and for scientists to drill and take samples from below the seabed to test for salinity. Known as Expedition 501, a collaboration between more than a dozen countries was born. Three drilling sites were set up in the waters south of Martha’s Vineyard and Nantucket. Aboard Lifeboat Robert, three gigantic pillars are lowered through the water column to the seafloor. Once at the bottom of the ocean, drill tools are lowered through the pillars. An empty core liner is lowered through the drill pipe, the pressure on the core is increased, and it penetrates into the seafloor to a certain depth (Gottschalk, 2019). This process fills the core with seafloor sediment samples.

There were samples containing water that was far below the oceans’ average salt content, but still too briny to be freshwater, and water samples that were technically safe enough to drink (Woodward et al, 2025b). This finding suggests that the water either used to be connected to a terrestrial waterway, or still is. When this work first began, researchers believed the secret aquifer could support a major city such as New York City for 800 years. Now, they believe the volume is even greater, that the aquifer stretches from the coast of New Jersey to Maine. Before this, there had been no project that had drilled into the seabed to find freshwater. Research takes time, and this secret aquifer will have to be analyzed in order to understand whether it is safe, where it came from, and how old it is. Dating the water will allow researchers to determine whether it is still connected to a terrestrial source and is renewable, or whether it is from glacial ice melt thousands of years ago. There is always a balance in nature, and extracting this water may cause unforeseen consequences. Extracting the water from the repository without harming the surrounding area is another story. And deciding who owns it and who uses it…

As someone who has an existential crisis every time I think too much about the current state of the world, this research gives me hope. Hope that maybe we aren’t too far gone and that there is still so much to discover. New ideas such as this one are so unfamiliar that they aren’t on the minds of conservationists or policy-makers. New ideas such as this one make me wonder how much is out there that is unknown and could potentially benefit us. 

Sources

Gottschalk, J. (2019, July 19). How a Drilling Ship Pulls Cores From 2.5 Miles Below the Sea – State of the Planet. State of the Planet. https://news.climate.columbia.edu/2019/07/19/drilling-ship-coring-process/

Jaynes, C. H. (2023, March 22). Global freshwater demand will exceed supply 40% by 2030, experts warn. World Economic Forum. https://www.weforum.org/stories/2023/03/global-freshwater-demand-will-exceed-supply-40-by-2030-experts-warn/

Krajick, K. (2019, June 20). Scientists Map Huge Undersea Fresh-Water Aquifer Off U.S. Northeast | Lamont-Doherty Earth Observatory. Columbia University. https://lamont.columbia.edu/news/scientists-map-huge-undersea-fresh-water-aquifer-us-northeast

Woodward, C., Kaster, C., & Ngowi, R. (2025a, September 5). Scientists tap fresh water under the sea, raising hopes for a thirsty world | AP News. AP News. https://apnews.com/article/freshwater-expedition-ai-501-cape-cod-5d62cae0f040d369b16d8400202f0a88

Woodward, C., Kaster, C., & Ngowi, R. (2025b, September 5). Takeaways from a hunt for “secret” fresh water under the North Atlantic seabed. AP News. https://apnews.com/article/freshwater-expedition-ai-501-cape-cod-1443df4f9ec09f74c23fad14a7225436