The Mediterranean Sea is an almost enclosed sea between Europe, Africa and Asia, connected to the Atlantic through the narrow Strait of Gibraltar. It covers less than one percent of the global ocean surface yet supports an exceptional share of marine species, including many found nowhere else.
Its long human history, dense coasts and restricted water exchange make it culturally rich and ecologically distinctive—and highly exposed to warming, pollution, overuse and habitat loss.
Where is the Mediterranean Sea?
The basin stretches from Gibraltar in the west to the Levant in the east. The Dardanelles and Bosporus connect it with the Black Sea through the Sea of Marmara, while the human-made Suez Canal links it with the Red Sea.
Geographers divide it into western and eastern basins and many regional seas, including the Adriatic, Aegean, Ionian, Tyrrhenian, Ligurian and Balearic. Submarine ridges, trenches, islands and narrow straits create varied habitats and circulation.
Why is Mediterranean water salty?
Evaporation exceeds the freshwater supplied by rainfall and rivers across much of the basin. Saltier Mediterranean water flows out at depth through Gibraltar, while fresher Atlantic surface water enters to replace the loss. Temperature and salinity help drive an internal overturning circulation.
Salinity differs by place and depth. The eastern basin is generally warmer and saltier than the western, while river mouths and the Black Sea connection freshen local water.
A global biodiversity hotspot
UNEP reports that the Mediterranean holds up to 18 percent of known marine species despite its small area. Habitats range from rocky shores and lagoons to canyons, cold-water corals and deep plains. Endemic species include Posidonia oceanica, whose meadows create nurseries, store carbon and protect sediment.
Marine mammals, sea turtles, sharks, rays, seabirds and commercially important fishes cross political borders. Effective protection therefore requires regional monitoring and cooperation.
A sea changing quickly
The Mediterranean is a climate-change hotspot. Marine heatwaves stress corals and seagrass and favour shifts in species distributions. Warming and the Suez connection contribute to the establishment of non-indigenous species, especially in the eastern basin.
Dense coastal development, tourism, shipping, fishing, wastewater, nutrient input and plastics add cumulative pressure. The basin’s semi-enclosed geography means persistent pollution can circulate and accumulate.
Why the Mediterranean matters to people
Coastal communities depend on fisheries, ports, tourism and cultural landscapes. The sea has connected languages, trade, science and art for millennia. Its health supports food, jobs, recreation, climate resilience and identity.
What a sustainable future needs
Priorities include greenhouse-gas reduction, effective marine protection, sustainable fisheries, clean wastewater, circular material use, seagrass and wetland protection, responsible shipping and shared open data. Local projects matter most when connected to basin-wide goals and community knowledge.
Continue with seagrass meadows and Posidonia, the restored overview of the Mediterranean Sea Decade, and ways to take part.
Frequently asked questions
Is the Mediterranean an ocean?
No. It is a sea connected to the Atlantic Ocean. Its partial enclosure strongly influences circulation and salinity.
Which countries border the Mediterranean?
More than 20 sovereign states have Mediterranean coastlines across southern Europe, North Africa and western Asia; the exact count depends on territorial definitions.