The most popular attraction of Santorini is the volcano. It is an underwater active volcano but there are two residual volcanic islands, Palaia Kammeni and Nea Kammeni, opposite Santorini. Before the several volcanic eruptions that occurred throughout the years, some of which were submarine, the size and the shape of Santorini were quite different. It was a much larger, round island, hence its name used to be Strogili (=circular).
Today the result of these eruptions is the creation of five separate islands, Santorini, Therasia, an uninhabited island called Aspronisi and the volcanic islands of Palaia Kammeni and Nea Kammeni. They compose a nice sight across the Aegean Sea, facing Santorini, and you can visit them as well. The existence of the volcano is visible all over the island of Santorini, especially on the bizarre beaches that are covered, in their majority, in black sand and pebbles made of solidified lava. The red volcanic rocks in Red beach, which reminds a lunar landscape, form a rare sight.
On the island of Palaia Kammeni there are hot springs known for their beneficial and therapeutic effects. The waters there contain sulfur and you can please yourself with an alternative mud bath. It is necessary that you swim in these waters to take your experience to a whole new level. To top it all, from there you can admire the breathtaking caldera from a different point of view that will completely amaze you.