The Ionian Sea is an elongated bay of the Mediterranean Sea. It is connected to the Adriatic Sea to the north, and is bounded by Southern Italy, including Calabria, Sicily, and the Salento peninsula to the west, southern Albania (and western Apulia, Italy) to the north, and the west coast of Greece, including the Peloponnese.
All major islands in the sea, which are located in the east of the sea, belong to Greece. They are collectively named the Ionian Islands, the main ones being Corfu, Kefalonia, Zakynthos, Lefkada, and Ithaca.
There are ferry routes between Patras and Igoumenitsa, Greece, and Brindisi and Ancona, Italy, that cross the east and north of the Ionian Sea, and from Piraeus westward. Calypso Deep, the deepest point in the Mediterranean at 5,109 m (16,762 ft), is in the Ionian Sea, at 36°34′N 21°8′E / 36.567°N 21.133°E / 36.567; 21.133. The sea is one of the most seismically active areas in the world.