Strait of Gibraltar, narrow passage connecting the Mediterranean Sea on the east with the Atlantic Ocean on the west. It separates northern Africa from the Rock of Gibraltar on the southernmost point of the Iberian Peninsula. The strait is 60 km (40 mi) long and varies in width from 13 to 39 km (8 to 24 mi). A channel 8 km (5 mi) wide, traversing the center of the strait, has a depth of 300 m (1,000 ft). A continuous current enters from the Atlantic Ocean, and tidal currents ebb and flow along the European and African shores. A westerly flowing undercurrent carries off the salty surplus waters of the Mediterranean Sea. The eastern end of the Strait of Gibraltar is flanked by the Pillars of Hercules.