Greece is situated in southeast Europe on the Mediterranean. The mainland consists of the following regions: Central Greece, Peloponnese, Thessaly (east/central), Epirus (west), Macedonia (north/northwest) and Thrace (northwest). Euboea, the second-largest of the Greek islands, lying to the east of the central region, is also considered to be part of the mainland region. The Peloponnese peninsula is separated from the northern mainland by the Isthmus of Corinth. The northern mainland is dissected by high mountains (such as the Pindus) that extend southwards towards a landscape of fertile plains, pine-forested uplands and craggy, scrub-covered foothills. The islands account for one-fifth of the land area of the country. The majority are thickly clustered in the Aegean between the Greek and Turkish coasts. The Ionian Islands are the exception; they are scattered along the west coast in the Ionian Sea. The Aegean archipelago includes the Dodecanese, lying off the Turkish coast, of which Rhodes is the best known; the Northeast Aegean group, including Chios, Ikaria, Lemnos, Lesvos and Samos; the Sporades, off the central mainland; and the Cyclades, comprising 39 islands (of which only 24 are inhabited). Crete, the largest island, is not included in any formal grouping.