The Gulf of Corinth or the Corinthian Gulf (Greek: Κορινθιακός Κόλπος, romanized: Korinthiakós Kólpos, Greek pronunciation: [koɾinθiaˈkos ˈkolpos]) is a deep inlet of the Ionian Sea, separating the Peloponnese from western mainland Greece.

The gulf is bordered by the large administrative divisions (regional units): Aetolia-Acarnania and Phocis in the north, Boeotia in the northeast, Attica in the east, Corinthia in the southeast and south and Achaea in the southwest.

The tectonic movement across the gulf is comparable to parts of Iceland and Turkey, growing by 10 mm (0.39 in) per year.

[2] The gulf was created by the expansion of a tectonic rift due to the westward movement of the Anatolian Plate, and expands by 10 mm (0.39 in) per year.

[6] The main cities and towns that lie next to the gulf are, from the northwest clockwise, and grouped by regional unit: All tributaries are listed west to east.