The island of Lesvos has an extension of 1,630 sq. km and is the biggest Greek island, next to Crete and Evia, while it has a population of 88,610 inhabitants. Lesvos, a volcanic island, has suffered from many earthquakes, while historians, claim that many cities were buried in the sea. Despite the rich vegetation, there are no major rivers, nor lakes, yet there are falls in the northern part of the island, the most known being Evergetoulas, Tenagion, Sedountas and Vourkas in the area of Plomari and Almiropotamos in Vrissa. The island has many mountains, the highest being Lepetimno in the north, with Profitis Ilias being its highest peak (968 m.). Other mountains are: Olimbos (967 m.), Psilokoudouno (914 m.), Roditis in Megalohori (845 m.), Kouratsonas (785 m.) between Vatoussa and Parakila, and Profitis Ilias (799 m.). The fauna in Lesvos is of a wide variety. The salt-mines in Kaloni are the permanent residence of 50 pairs of herons, while the area "houses" other species of rare birds, from time to time. In the caves of Skala in Eressos, a few mediterranean seals have found refuge, while in the monastery of Limonas, wild birds are sheltered. Olive groves abound on the island, making Lesvos an island known for its oil production, while the vineyards, in Plomari produce excellent ouzo and top quality wine. The cultivation is fortified by the island's mild climate, which is humid and mediterranean with warm winters. The average temperature in the summer is 30 °C, while in the winter it drops to 10.4 °C. The people of Lesvos are kind and helpful, they like foreigners and they treat their guests with love and affection.