The Strait of Gibraltar (Arabic: مضيق جبل طارق, Spanish: Estrecho de Gibraltar) is the strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Spain from Morocco. The name comes from Gibraltar, which in turn originates from the Arabic Jebel Tariq (جبل طارق) meaning mountain of Tariq. It refers to the Ummayad Berber general Tariq ibn-Ziyad who led the Islamic conquest of Hispania in 711. It is also known as the Straits of Gibraltar or STROG (Strait Of Gibraltar), the latter being in naval use.
There are 13 km (8 miles) of ocean separating Europe from Africa at the strait's narrowest point. The strait depth ranges between . A ferry commutes between the two continents. The Spanish part of the strait is protected under the El Estrecho Natural Park.
On the northern side of the Strait is Spain and Gibraltar, while on the southern side is Morocco and Ceuta, a Spanish exclave in North Africa. Its boundaries were known in antiquity as the Pillars of Hercules. There are several small islands, such as the disputed Isla Perejil, that are claimed by both Spain and Morocco..
Due to its location, the strait is widely used for illegal immigration from Africa to Europe.
The Straits are an important shipping route from the Mediterranean to the Atlantic. There are ferries that operate between Spain and Morocco across the strait, as well as between Spain and Ceuta and Gibraltar to Tangier.
Internal waves (waves at the density boundary layer) are common in the strait. Like traffic merging on a highway, the water flow is constricted in both directions because it must pass over a shallow submarine barrier, the Camarinal Sill. When large tidal flows enter the Strait, internal waves are set off at the Camarinal Sill as the high tide relaxes. The waves—sometimes with heights up to travel eastward. Even though the waves occur at great depth and the height of the waves at the surface is almost nothing, they can be traced in the sunglint because they concentrate the biological films on the water surface, creating slight differences in roughness. The waves flow eastward, refract around coastal features; can be traced for as much as , and sometimes create interference patterns with refracted waves.