Nisyros Island is situated in the Aegen Sea, between the islands of Kos and Tilos. Not a big island, some 3 kilometres by 4 kilometres is the most famous because of its caldera that was created 150,000 years ago. There were 3 separate eruptive stages during its creation, ranging from explosive and effusive andesitic eruptions to effusive and extrusive dacitic and rhyolitic activity. This is the only active volcano in the eastern Aegean in Greece and the materials like black lava, pumice, white and red rust are used to built the houses, the temples and castles. Other attractions of the islands are hot springs. The coast is mainly rocky or pebbled, but there are also a few sandy beaches. The biggest town is Mandraki, with whitewashed houses, as well as some stone houses.