Mediterranean Sea million years ago (mya) in less than two years by the Zanclean flood. Water poured in from the Atlantic Ocean through a newly breached gateway now called the Strait of Gibraltar at an estimated rate of about three orders of magnitude (one thousand times) larger than the current flow of the Amazon River. The Mediterranean Sea has an average depth of and the deepest recorded point is in the Calypso Deep in the Ionian Sea. The coastline extends for . A shallow submarine ridge (the Strait of Sicily) between the island of Sicily and the coast of Tunisia divides the
Mediterranean Sea sea in two main subregions: the Western Mediterranean, with an area of about 850 thousand km (330 thousand mi); and the Eastern Mediterranean, of about 1.65 million km (640 thousand mi). A characteristic of the coastal Mediterranean are submarine karst springs or s, which discharge pressurised groundwater into the coastal seawater from below the surface; the discharge water is usually fresh, and sometimes may be thermal. The Mediterranean basin and sea system was established by the ancient African-Arabian continent colliding with the Eurasian continent. As Africa-Arabia drifted northward, it closed over the ancient Tethys Ocean which had earlier separated the