Santorini's volcano!
Or more precisely, two black lava islets in the very center of the overall crater that forms the island.
Nea Kameni, the younger islet, most visible here, measures about 2.5 km in length.
It appeared as a result of numerous eruptions between May 1707 and September 1711.
Palea Kameni, an older islet, is located just behind; from here, it merges with the first.
In recent years the volcano has been rather calm, so it is possible to visit it without great risks...