The Balkan Peninsula is an area of southeastern Europe surrounded by water on three sides: the Adriatic Sea to the west, the Mediterranean Sea (including the Ionian and Aegean seas) and the Marmara Sea to the south and the Black Sea to the east. Its northern boundary is often given as the Danube, Sava and Kupa Rivers. The Balkan Peninsula has a combined area of about 490,000 km2 (189,000 sq mi).