A water mass, formed in the arid eastern Mediterranean, that flows westward, sinking in the Algero-Ligurian and Alboran basins to a depth of approximately 500 m due to its high salinity (36.5–39.1‰). This dense water flows into the Atlantic Ocean through the relatively shallow Straits of Gibraltar at a depth below 150 m, while above it lighter, Atlantic water flows eastward into the Mediterranean Sea. The Mediterranean water in the Atlantic then sinks to about 1000 m, where it forms a clearly identifiable water mass.