The Tyrrhenian Sea is part of the Mediterranean Sea off the western coast of Italy.

It is bounded by Corsica and Sardinia (west) Liguria (north), Tuscany, Latium, Campania, and Calabria (east), and Sicily (south).

The maximum depth is 3785 m.

The Tyrrhenian Sea is situated near the African-European Fault ; therefore mountain chain and active volcanoes (mount Marsilii) are in its depths. Winds are Mistral from Rhone valley, Libeccio from south-west, Scirocco and Ostro from south.

There are five exits from the Tyrrhenian Sea:

• the Strait of Messina between Sicily and Messina on the toe of Italy, 3 km wide;
• the Corsica Channel between Italy and Corsica, about 80 km wide;
• the Strait of Bonifacio between Corsica and Sardinia, 11 km wide;
• an unnamed strait between Sardinia and Tunisia, about 200 km wide; and
• the Strait of Sicily between Tunisia and Sicily, about 160 km wide.

In Greek mythology, the cliffs above the Tyrrhenian Sea were said to house the four winds kept by Aeolus.