A 2D numerical model study of a regional scale thermal anomaly along the north Spanish border of the Mediterranean Sea indicates strong lateral offshore heat transport due to groundwater circulation. Although the area is situated at the western side of the Valencia Trough rift zone, the amplitude and wavelength of this coupled negative-positive anomaly cannot be explained by conductive heat flow. A strong hydraulic gradient onshore and a thick layer of permeable Mesozoic limestones should permit lateral advection of pore water about 30 km off-shore where discharge creates anomalous temperature gradients. This result underscores the importance of deep groundwater flow even in the interpretation of regional scale thermal anomalies in rifting zones. ¿ American Geophysical Union 1990