Offshore fresh (or freshened) groundwater: Research achievements and future perspectives

Abstract Offshore fresh or freshened groundwater (OFG) is an important but under-represented component of coastal hydrogeological and climate systems. Recent advances in geophysical imaging, offshore drilling, numerical modelling, and machine learning have improved understanding of OFG distribution, dynamics, and connectivity with onshore aquifers. Remaining challenges include volumetric quantification, recharge history, ecological implications, and governance. OFG may complement coastal water-resource portfolios, but sustainable utilisation requires integrated management, environmental safeguards, and updated legal frameworks at national and international levels.