Which gulf in Greece is crossed near its western end by the Rio–Antirrio Bridge?

The gulf in Greece crossed near its western end by the Rio–Antirrio Bridge is the Gulf of Corinth. The bridge spans the Rion Strait, the narrow waterway linking the Gulf of Corinth with the Gulf of Patras and the Ionian Sea.

The Gulf of Corinth separates the Peloponnese from mainland Greece. It stretches roughly 130 kilometres from the Rion Strait in the west to the Isthmus of Corinth in the east, where the Corinth Canal provides a separate route between the Gulf and the Saronic Gulf.

The Rio–Antirrio Bridge, officially the Charilaos Trikoupis Bridge, opened in 2004. Its location presented major engineering challenges: deep water, loose seabed sediments, strong winds, earthquakes and continuing tectonic movement. The gulf is widening by about 10 millimetres per year, so the bridge was designed to tolerate substantial movement.

A common mix-up is the Gulf of Patras, which lies immediately west of the bridge. The bridge crosses the Rion Strait between the two gulfs, but its eastern side is conventionally identified with the Gulf of Corinth.