The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto to the northwest and the Po Valley. The countries with coasts on the Adriatic are Albania, Bosnia and Herzegovina, Croatia, Italy, Montenegro, and Slovenia.

The Balkans, corresponding partially with the Balkan Peninsula, is a geographical area in southeastern Europe with various geographical and historical definitions. The region takes its name from the Balkan Mountains that stretch throughout the whole of Bulgaria. The Balkan Peninsula is bordered by the Adriatic Sea in the northwest, the Ionian Sea in the southwest, the Aegean Sea in the south, the Turkish straits in the east, and the Black Sea in the northeast. The northern border of the peninsula is variously defined. The highest point of the Balkans is Musala, 2,925 metres (9,596 ft), in the Rila mountain range, Bulgaria.