Where Does the Mediterranean Sea Begin? Defining Its Boundaries

The Mediterranean Sea is a semi-enclosed marginal sea of the Atlantic Ocean, bounded by three continents. Its "start" is defined by its connections to adjacent waters:

• West: Strait of Gibraltar (14 km wide) – the sole natural connection to the Atlantic Ocean, separating Spain and Morocco.
• Northeast: Dardanelles Strait → Sea of Marmara → Bosporus Strait – the Turkish Straits system linking to the Black Sea.
• Southeast: Suez Canal (artificial, 193 km) – connects to the Red Sea and Indian Ocean.

Geographically, the Mediterranean extends from 5.5°W (Gibraltar) to 36°E (Levantine coast) and 30°N (Libya) to 46°N (Gulf of Lion). It comprises several sub-seas: Alboran, Balearic, Ligurian, Tyrrhenian, Ionian, Adriatic, Aegean, and Levantine.

Its unique circulation—Atlantic inflow at surface, hypersaline outflow at depth—makes it a concentration basin. The Mediterranean has been a cradle of civilizations, a trade highway, and a biodiversity hotspot with high endemism.