Arm of the Mediterranean Sea indenting the northwestern coast of Italy. It extends between Liguria and Tuscany (north and east) and the French island of Corsica (south). It receives many rivers that originate in the Apennines, and it reaches a depth of more than 9,300 feet (2,850 m) northwest of Corsica. The sea includes the Gulf of Genoa in the north and is connected through the Tuscan Archipelago in the southeast with the Tyrrhenian Sea.