Slovenia is located in the north-west of the Balkan Peninsula and, in a small part, in the north of the Istrian peninsula. The country has access to the sea: part of the Slovenian territories (about 45 km) lies on the coast of the Adriatic Sea's Trieste Gulf.

The bay is relatively shallow, with a depth of 16 to 37 m. Geographers territorially refer it to a larger, Venetian Gulf. The Adriatic, in turn, is considered part of the Mediterranean Sea, and the Trieste Bay is its northernmost extremity.