The sea that separates Italy and Yugoslavia?
The sea that is located in between the countries of Italy and Yugoslavia is called the 'Adriatic Sea'. In reality it's an arm of the Mediterranean Sea, and it coasts with the following countries: Italy, Albania, Croatia, Bosnia-Herzegovina, Montenegro and Slovenia.
There is no sea between Serbia and Italy. When Serbia was part of Yugoslavia, sea between Yugoslavia and Italy was called Adriatic sea. Today, 4 former Yugoslav republics lies on Adriatic coast: Slovenia, Croatia, Bosnia and Herzegovina and Montenegro. So, your question could be: What is the sea between Slovenia and Italy (or Croatia and Italy for example), and than the answer would be : Adriatic sea.
Italy is a peninsula and is almost all coast! The majority of the borders of Italy are coast lines, with just the Northern portions bordering France, Switzerland, Austria and Yugoslavia. It is bordered by the Tyrrhenian Sea to the west, the Adriatic Sea to the east, and the Mediterranean Sea to the south.
Greece is entirely in the Mediterranean Sea. The eastern coast of Greece is on a body of water of the Mediterranean Sea which is called Ionian Sea and separates Greece and Italy. The western coast of Greece is on a body of water of the Mediterranean Sea which is called Aegean Sea and which separates Greece and Turkey. The Greek coast on the Aegean Sea is longer than that on the Ionian Sea.