The Gulf of Koper or Koper Bay (Slovene: Koprski zaliv, Croatian: Koprski zaljev, Italian: Golfo di Capodistria) is located in the northern part of the Adriatic Sea, and is a part of the Gulf of Trieste.

The gulf, named after the city of Koper, is part of the Slovene Riviera and is entirely located in Slovenian territory. Crossed by the river Rižana, it is 18 km large and spans from Debeli Rtič, next to the borders with the Italian town of Muggia; to Rt Madona, a cape in the town of Piran, that is also the northernmost point of the Gulf of Piran.

The towns of Koper, Izola and Piran (the northern shore), along with the villages of Ankaran, Bertoki, Jagodje, Dobrava, Strunjan and Fiesa, are located by the gulf.

• Gulf of Piran
• Gulf of Venice
• Gulf of Trieste

• Map of the Gulf of Koper (iTouchMap)