Ionian Sea: The Ionian Sea is a part of the Mediterranean Sea that lies between Italy and Greece. Croatia's southernmost islands, such as Korcula and Mljet, are located in the Ionian Sea.
Kupa River: The Kupa River is the largest river in Croatia. It flows from Slovenia through Croatia and into Serbia, where it joins the Sava River.
Sava River: The Sava River is the second largest river in Croatia. It flows from Slovenia through Croatia and into Serbia, where it joins the Danube River.
Drava River: The Drava River is the third largest river in Croatia. It flows from Italy through Austria, Slovenia, Croatia, and Hungary, where it joins the Danube River.
Danube River: The Danube River is the fourth largest river in Croatia. It flows from Germany through Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, and Romania, where it empties into the Black Sea.