The term is defined by the European Environment Agency as applying to the land areas of Europe that border on the Mediterranean Sea, and the corresponding territorial waters.

[5] The region has generally hilly terrain and includes islands, high mountains, semi-arid steppes and thick Mediterranean forests, woodlands, and scrub with many aromatic plants.

Coastal wetlands are home to endemic species of insects, amphibians and fish, which provide food for large flocks of waders and dabbling ducks.

The shallow coastal waters hold huge Posidonia beds, underwater meadows that harbor rare crustaceans, sponges and Ascidiacea (sea squirts).

[8] A 2011 study of spiders in the coastal dunes of Portugal showed that the primary factor in beta diversity was a broad-scale gradient of mediterraneity.

[1] The region contains about 1.6% of the world's dry land but has about 10% of the known vascular plant species, with over 25,000 identified to date.

The ecology is threatened by habitat loss or degradation from fishing, pollution, climate change, eutrophication and alien species.