Tyrrhenian Sea, part of the Mediterranean Sea, bordered by the Italian peninsula and the islands of Corsica, Sardinia, and Sicily. The Strait of Messina connects it to the Ionian Sea; the Ligurian Sea joins it on the north. Near its center the Tyrrhenian reaches a maximum depth of 12,300 feet (3,750 m). Several famous islands, including Elba, Capri, and Stromboli, lie within this part of the Mediterranean. The principal ports are Naples, Palermo (Sicily), and Cagliari (Sardinia).