The most famous attraction of Santorini and at the same time the one that is responsible for its unique beauty and the special, wild, but also romantic atmosphere. The volcanic activity gradually created a huge cavity which was flooded by the sea, the famous caldera. According to researchers, the volcano was destroyed and created again 12 times during the last 400,000 years. The most recent big eruption is the one noted around 1650 BC when Santorini had the name Strogili, since it was a single island with Thirasia and Aspronisi, thus constituting a circular island. The seismic activity at that time must have been constant for months, warning the inhabitants, who probably abandoned the island before the big eruption. This is proven by the fact that no human skeleton was found beneath the ash. This specific eruption was so big that it is calculated that during approximately six days, 90 billion tons of melted rock were thrown in the air. The volcanic ash, after having covered the entire island, traveled around the whole world, with ash having been detected in the glaciers of Greenland, while it caused a “volcanic winter”, reducing the average temperature of the earth by 1-2 degrees. The eruption also caused a huge tidal wave, which was probably responsible for the destruction of the Minoan civilization (in Crete). 1500 years later, milder volcanic activity created the undersea volcano, whose tops are Nea (New) and Palea (Old) Kameni. The last eruption occurred in 1950 and since then it has remained calm, with only its hot springs and hot gases revealing its existence. Nowadays there are seven craters in Nea Kameni, one in Palea Kameni and the undersea crater Kolumbos, at the southern part of the island, outside the caldera. The visitors can walk on the craters as well as swim in the hot springs. Naturally, the signs of the volcano are visible throughout Santorini. Daily boat excursions to the volcano are organized, an excursion that also includes the hot springs and occasionally Thirasia (depending on the route you choose). Wear comfortable, closed shoes for the volcano and do not forget to take your swimming suit in order to swim in the hot springs.