To understand the Mediterranean you have to first must know that this large inland sea has been fundimental to the story of humanity in the western world. For the earliest legends of mystery and intrigue that brought the settlers and colonists and then later empires as western civilisation grew from the cradle. From there it has seen the galleys of the Greeks and Romans clash with the Persians and Cartheginians. Later the ships of the Ottoman Empire and Christendom and in recent times the steel warships of WW1 and WW2.
For the diver the sea offers a variety of diving. From the west at the Gates of Hercules is Gibralter. This is widely known as the Strait of Gibralter and is an important area which has the strategic position of Gibralter controlling what flows to and fro. The Atlantic Ocean funnels through here creating powerful currents. The edge of diving in the Mediterranean is here. Spain, Majorca and France all have diving sites in this region.
Moving into the middle of the map is Italy where Corsica and Malta are immediately noticeable. Less well known are the dive sites in the Ionian and Agean seas. Croatia is an unlikely but rising star in the dive scene. The Greek Islands surrounding Greece are a classical place for diving. At Turkey there is opportunity for diving and the Black Sea is a tempting spot to dive the fringes. Bulgaria and Romania also have limited dive sites.
Finally at the eastern edge of the Mediterranean is Egypt and Israel. Egypt is an immediate favourite for most divers with plenty of dive sites and famous wrecks.