How does the Strait of Gibraltar connect the Atlantic Ocean and the Mediterranean Sea?

The Strait of Gibraltar serves as a vital 36-mile-long (58 km) channel that connects the Atlantic Ocean to the Mediterranean Sea.12

This connection is maintained through a significant exchange of water between the two bodies. A surface current generally flows eastward from the Atlantic into the Mediterranean. Conversely, a deeper, westward-flowing current—consisting of heavier, colder, and more saline water—occurs below a depth of approximately 400 feet (120 metres). This continuous exchange is essential, as it prevents the Mediterranean from becoming a shrinking salt lake due to high evaporation rates.13

The strait is geographically defined by the Pillars of Heracles, which include the Rock of Gibraltar to the north and either Mount Hacho or Jebel Moussa to the south. Beyond its hydrologic role, the strait remains a critical shipping route for international commerce.1