Linosa is a volcanic island resting on a sandy seabed. Its activity began at a depth of about 1,000m. It is formed by four eruptive centers: Mt. Rosso, the highest summit (197m above sea level), Mt. Vulcano in the south-east, Mt. Bandiera, at the foot of which lies the town, and Mt. Nero facing the sea in Cala Pozzolana di Ponente. The uncontaminated seabed is full of life and it is not difficult to meet invertebrates with bright colors, nudibranch's eggs fine as laces, red and purple starfish, holothurians, ophiuroids, and sea urchins of various species.