Naples, Gulf of

an inlet of the Tyrrhenian Sea, off the western coast of Italy. The Gulf of Naples juts inland for 22 km; it is 30 km wide at the entrance and has depths to 451 m. The bay is bounded in the south by the mountainous Sorrento Peninsula. Mount Vesuvius is on the eastern shore. The coast, which is protected from the north winds, has a mild climate and is densely populated. The major port city of Naples is on the gulf’s northern shore.