Treasures under the seafloor

A webseries on the GEOMAR YouTube channel

Expedition M196 took a research team to the Gulf of Corinth off the coast of Greece in December 2023. There, the scientists investigated a newly discovered groundwater occurrence in the seabed ("offshore-freshened" groundwater, OFG). They carried out measurements to collect both electromagnetic and geochemical porewater and groundwater data. Combined with existing borehole data, their aim was to derive the spatial extent of OFG in the region and to understand its possible connection to the terrestrial groundwater system.


Groundwater quality is deteriorating in many regions of the world, leading to increasing pressure on water resources, particularly in coastal regions. In order to alleviate water scarcity under changing climatic conditions, alternative water sources such as offshore-freshened groundwater (OFG) have come into scientific focus. It is estimated that the volume of groundwater in OFGs worldwide amounts to half a million cubic kilometres. This volume corresponds to the fresh water consumption of an entire century, based on today's consumption. Although OFGs are a global phenomenon, the spatial extent, volume and geological control of OFGs are poorly understood as discoveries are mainly based on chance discoveries in boreholes. There are few studies that combine the point data from boreholes with regional measurements to adequately constrain the spatial extent of OFGs. In addition, questions about the connection between OFGs and their terrestrial counterparts are still largely unanswered - something the expedition team wants to change.

A web series by Hannes Schuler

Link to the YouTube Series GEOMAR