The Gulf of Patras (Greek: Πατραϊκός Κόλπος, Patraikós Kólpos) is a branch of the Ionian Sea. On the east, it is closed by the Strait of Rion between capes Rio, Greece and Antirrio, near the Rio-Antirio bridge, that is the entrance of the Gulf of Corinth. On the west, it is bounded by a line from Oxeia island to Cape Araxos. To the north it is bounded by the shore of Aetolia-Acarnania in continental Greece, and to the south by Achaea in the Peloponnese peninsula. It is 40–50 km long, 10–20 km wide, and has an area of 350–400 km2.
The port city of Patras lies to the southeast and is the only major port on the gulf. It serves ferries to Ancona and Brindisi in Italy along with Kefallonia. On the northern shore Missolonghi also has a port. There are beaches in the south, the east and parts of the north. The old ports of Rio and Antirio lie east of the Gulf, and there is a ferry service which complements the traffic over the Rio-Antirio bridge. The gulf is rich in fish.
A number of major naval battles took place in the Gulf of Patras: the Battle of Patras in 1772, and the Battle of Lepanto in 1571, one of the largest naval battles ever fought. Lepanto itself lies further east, in the Gulf of Corinth.
The following rivers flow into the Gulf of Patras:
Coordinates: 38°15′N 21°30′E / 38.250°N 21.500°E