A low-salinity anticyclonic eddy was found during a field study of the shelf/slope front off the northeast Spanish coast in July 1983. The eddy was associated with a tongue of low-salinity, cold water that originated in the Gulf of Lions. Hydrographic stations indicated the presence of multiple salinity-inversion layers. In particular, a relative salinity maximum layer was found at the base of the eddy, which can be traced through the study area along the same isopycnal surface. This suggests the thermohaline intrusion of near-surface, warm, high-salinity, open-ocean water along the frontal boundary. The anticyclonic eddy also induced a strong up welling and, consequently, a high biological production at the coast. Subduction along the coastal front seems to provide major transport of particulate material into the open sea.