Santorini stretches over 76km2 with its coastal area being 69km long. It is still considered as one of the active volcanoes of the wider Mediterranean Sea basin. In geological terms, it is part of the South Aegean active volcanic arc.
- It is one of the few places in the world where these architectural cave houses, called "Iposkafa", are maintained while being carved within the volcanic ground.
- Santorini's volcanic settlement is known worldwide and attracts international scientific interest. It includes the islands of Thera, Therassia as well as the islets of Aspronisi, Palea and Nea Kammeni where the volcano's crater lies.
The Caldera walls constitute steep cliffs 150-350m high, where several successive layers formed as a result of volcanic eruptions can be spotted together with all different types of rock such as redstone, black rock and Santorini's soil ("aspa").
Caldera, similarly to the island of Santorini itself, has been characterised as a destination of exquisite natural beauty.
There are 13 villages.
The climate is mild and wet with multiple north and north-eastern winds that render summer high temperatures rather tolerant.