The geological history of the Mediterranean sea started about 250 million years ago, but only in the following millions of years did the movements of the continental plates give the Mediterranean sea a shape similar to the present one. The modern Mediterranean sea, with 22,500 km of shores and stretching over 4000 km from Gibraltar to the eastern coasts, covers 2.5 million sq. km, equal to 1% of the Earth’s seas. Its geological development, conditioned by the movements of the continental African and Eurasian plates and by the subducted lithosphere, drove the formation of the mountain chains that border its basin, over 5,000-m deep. Today the Mediterranean sea is not just a vital hydrogeological system for over 30 million people that live along its shores, but also one of the most complex tectonic regions on Earth and a natural laboratory for modern scientists. Volcanic eruptions and earthquakes show that disastrous events have taken place in this region and changed its history. These include the eruption in Thira during the Bronze Age, of the Vesuvius in 79 A.D., as well as strong sea-quakes, like those in Crete in 365 A.D. or in Messina in 1908, which caused deaths and severe damage along the shores. Major climatic and tectonic changes have brought about significant variations in the sea level, capable to cause the draining of the entire Mediterranean sea or the flooding of the Black sea, thus affecting man’s activities throughout history.