The reserve is 1361,85 Ha big and covers all the island. Even before arriving at the harbour the volcanic structure of the island can be seen and the shape is easily recognizable. There are three volcanic frames: The Grand Cratere, Vulcanello and the Piano Crater. This last one is the most ancient and what remains nowadays is a caldera whose walls are clearly visible from the top of the Gran Cratere. The caldera is located in the southern side of the isle that is characterised by 2 little mountains as well: Monte Aria (499 mt) and Monte Lentìa (184 mt). This part is the only one where there are vineyards, orchards and pastures. The Gran Cratere (391 mt) is the youngest volcano and it is worth climbing the top. The fumaroles are the evidence that the volcano is active and the panorama once on the top is astonishing. The colours of the sulphur and of the oxidized iron vary from the intense yellow to the mild ochre passing by all the possible shades, all around the blue sea and the clear sky: is it the hell or the paradise?
Vulcanello is linked to the isle by an isthmus and represents what remains of an ancient volcano risen from the sea and eroded by the sea itself.
The thermal area is located around the sulphurous mud lake where hot fumaroles made up by sulphur and clay comes to the surface. The hot temperature, the sulphur and the acidity of the mix have good proprieties to heal the skin and are considered highly therapeutic. One of the goal of the reserve is to preserve this area and all the micro organisms such as alga, bacterium and diatoms that live in the muds.