Researchers discover large freshwater deposits under the North Sea

A research team from Kiel has identified a significant band of brackish to nearly fresh water located deep beneath the North Sea seabed. The discovery was made in a 35 by 25 kilometer area in the southeastern North Sea, between Amrum and Helgoland.

Using the research vessel Alkor, scientists conducted electromagnetic measurements and seismic profiling over 320 kilometers of survey lines. The water layer is situated approximately 100 to 250 meters below the seabed and measures between 50 and 150 meters in thickness. While seawater typically has a salinity of about 35 Practical Salinity Units (PSU), the detected band showed a much lower salinity, calculated between 3.5 and 16.3 PSU.

Researchers believe the water originated from glacial meltwater during ice ages. Under immense pressure, this meltwater was forced into sediment layers, displacing the existing saltwater. The findings were published on October 17, 2026, in the journal Communications Earth & Environment. Scientists suggest that similar deposits may extend far beyond the specific area studied.