Santorini is actually a small group of five islands, being the remnants of the volcanic island that exploded around 1600 BC. They form a broken ring around the crater of the volcano. The largest island is Thera, which contains several towns. Then comes Therasia, which holds just one town. The remaining three islands are uninhabited: Aspronisi is a tiny speck in the largest channel between Thera and Therasia; Palea Kameni is a small island near the middle of the crater; and Nea Kameni is in the centre of the crater, being a newly formed island that broke the surface only in 1704 when new volcanic activity pushed it up from the sea.