The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges. The Adriatic Sea is a part of the Mediterranean Sea.

The western coast is Italian, while the eastern coast runs mostly along Croatia, but lesser parts belong to Slovenia, Bosnia and Herzegovina, Montenegro, and Albania. Major rivers joining the Adriatic are the Reno, Po, Adige, Brenta, Piave, Isonzo (Soča), Neretva.