Kalymnos is 111 sq.km in area, 96 km in coastline, and it is 206 nautical miles from Piraeus. It is the seat of the prefecture to which Lipsi, Leros, Patmos, and Astipalaia also belong. The island's climate is mild, dry and very healthy. It is quite hot in winter and it can get a bit breezy in summer during nightfall. Its high and rocky mountains are one of its most significant sights. They divide the island into three ranges and form two big valleys and many smaller ones. The north range, which is the biggest, extends from east to west. Its highest peaks are "Panagia Kyra-Psili" (608m), "Calatiani" (589m), "Stavros" (418m), "Krios" (432m), "Pyrnari" (397m), and "Patelia" (433m). The middle range divides the valley of Vathis and Pothia. Its highest peaks are "Profitis Ilias" (680m) and "Maria" (655m). The highest peaks of the southern range are "Miroviglio" (498m) and "Kassala" (480m). Kalymnos has a population of about 17,000 inhabitants who are divided among three settlements, villages, and Kalymnos town, which has 12,000 inhabitants. Kalymnians are simple, gentle and hospitable people. Most fathers and sons are sponge divers. It is a dangerous craft which has cost the people many lives. Sponge production is their main source of income, but there are also many farmers and stock-breeders.