Greece (Greek: Ελλάδα, Elláda, Ancient Greek: Ἑλλάς, Hellás), also known as Hellas and officially the Hellenic Republic (Ελληνική Δημοκρατία, Ellīnikī́ Dīmokratía), is a country in southeastern Europe. Situated on the southern end of the Balkan Peninsula, Greece has land borders with Albania, the Republic of Macedonia and Bulgaria to the north, and Turkey to the east. The Aegean Sea lies to the east of mainland Greece, the Ionian Sea to the west, and the Mediterranean Sea to the south. Greece has the twelfth longest coastline in the world at 13,676 km (8,498 mi) in length, featuring a vast number of islands (approximately 1400, of which 227 are inhabited), including Crete, the Dodecanese, the Cyclades, and the Ionian Islands among others. Eighty percent of Greece consists of mountains, of which Mount Olympus is the highest at 2,917 m (9,570 ft).