Unlike the nearby Ischia and Procida islands, Capri is of karstic origin. It was initially joined to the Sorrento Peninsula, but was later submerged by the sea and then separated from the mainland, where today the strait of Bocca Piccola is located.
Capri has a complex morphological structure, with peaks of medium height (Mount Solaro 589 m and Mount Tiberio 334 m) and vast interior plateaus, including the main one called the "Anacapri".
Numerous grottoes and bays alternate with steep cliffs on this rugged coastline. The grottoes, hidden beneath the cliffs, were used in Roman times as nymphaeums for the sumptuous villas that were built here during the Empire. The most famous is undoubtedly the Blue Grotto, where magical light effects were described by many writers and poets.
Capri also features the famous Faraglioni, three small rocky islet stacks just off the shore which create a dramatic visual effect and landscape; some have even been given names to distinguish them from each other: Stella, which is attached to the mainland, Faraglione di Mezzo for the one lying between the other two and Faraglione di Fuori (or Scopolo) for the one farthest from the island.
The island contains many plant and animal species, some endemic and others rare, like the blue lizard, which lives on one of the three Faraglioni. The vegetation is typically Mediterranean, with a prevalence of agaves, prickly pears and gorse.
In Capri there are no longer any sources of drinking water; water supply is secured by underwater pipelines from the Sorrento peninsula. Electricity is supplied by a private company on the island.
The main inhabited areas on the island are Capri, Anacapri and Marina Grande while Capri's other bay, Marina Piccola, is less inhabited and more subject to the phenomenon of land speculation that has assailed the island from the early 1980s to today.