About 75% of Greece is mountainous and only about 20% of the land is arable. The country falls into four main geographical regions. Northern Greece includes portions of historic Epirus, Macedonia, and Thrace. It takes in part of the Pindus Mts. (which continue into central Greece); low-lying plains along the lower Nestos and Struma rivers; and the Khalkidhikí peninsula, on which Thessaloníki, Greece's second largest city, is located. Central Greece, situated N of the Gulf of Corinth, includes the low-lying plains of Thessaly, Attica, and Boeotia; Mt. Olympus (Ólimbos; 9,570 ft/2,917 m), the highest point in Greece; and Athens. Southern Greece is made up of the Peloponnesus. The fourth region of Greece comprises numerous islands (with a total area of c.9,600 sq mi/24,900 sq km), the most notable of which are Crete, in the Mediterranean; Kérkira, Kefallinía, Zákinthos, Lefkás, and Itháki, in the Ionian Sea; and the Cyclades, the Northern Sporades, the Dodecanese (including Rhodes, Évvoia, Lesbos, Khíos, Sámos, Límnos, Samothrace, and Thásos, in the Aegean. Greece has few rivers, none of them navigable.
The Greek people are only partly descended from the ancient Greeks, having mingled through the ages with the numerous invaders of the Balkans. Modern vernacular Greek is the official language. There is a small Turkish-speaking minority, and many Greeks also speak English and French. The Greek Orthodox Church is the established church of the country, and it includes the great majority of the population. The Greek primate is the archbishop of Athens, who recognizes the Ecumenical Patriarch of İstanbul. There is a small Muslim minority.