A deeply incised gorge is buried nearly 800 m beneath the floor of the Valencia Trough in the western Mediterranean Sea. The gorge is steeply cut more than 200m into Messinian evaporite deposits and has been mapped for more than 40 km. Published and unpublished seismic profiles show the total length to be nearly 300 km. The gorge is not aligned with any known large fluvial systems, and its orientation indicates that it may have been connected near Valencia with the Betic Strait, the portal in southern Spain proposed to link the Atlantic and the western Mediterranean. The Betic Strait was probably open at least through early Messinian time. Conservative estimates show that sea water flowing through the Valencia gorge at rates of 0.5 to 2 m/s could have refilled the western Mediterranean basins below 2000 m in less than 50 yr.