Short answers, pulled from the story.
The Mediterranean Sea is an intercontinental sea situated between Europe, Asia, and Africa. It is almost completely enclosed by land, bounded by the Levant in the east, Anatolia and Southern Europe in the north, and North Africa in the south, and it connects to the Atlantic Ocean through the Strait of Gibraltar.
The Mediterranean Sea covers about 2,500,000 square kilometers, which is 0.7% of the global ocean surface, and it includes fifteen marginal seas. Its average depth is 1,500 meters, and the deepest recorded point is the Calypso Deep in the Ionian Sea.
The Messinian salinity crisis was a period beginning about 5.96 million years ago when the Mediterranean became landlocked and essentially dried up, lasting some 630,000 years until about 5.3 million years ago. It left salt deposits on the basin floor more than three kilometers thick in places.
The Mediterranean Sea was last filled about 5.3 million years ago in less than two years through the Zanclean flood. Water poured in from the Atlantic Ocean through a newly breached gateway, now the Strait of Gibraltar, at an estimated rate about one thousand times larger than the current flow of the Amazon River.
Mare Nostrum, meaning 'Our Sea', was the name the Romans used starting with the Roman Empire founded by Augustus. For about 400 years Rome completely controlled the Mediterranean and nearly all its coasts from Gibraltar to the Levant, and it remains the only state ever to have controlled the entire coastline.
The Mediterranean Sea has been called a cemetery and a graveyard because of the large number of migrants who drowned there after their boats capsized. The Maltese president used the word in 2013, and in 2015 more than one million migrants crossed the sea into Europe, with over 700,000 landing in Italy between 2013 and 2018.
The Mediterranean Sea faces pollution, overfishing, invasive species, and marine heatwaves. The United Nations Environment Programme estimated that 650 million tonnes of sewage and other pollutants are dumped in each year, more than 65% of fish stocks lie outside safe biological limits, and invasive Indo-Pacific species enter through the Suez Canal.