The main islands in the group are: the island of S. Domino, the largest and the most popular for tourists and completely covered by a luxuriant pine forest in Pino d'Aleppo; the island of S. Nicola, the administrative, historical and religious capital; the island of Caprara which may owe its name to the caper plants or more probably to the presence of wild goats; the distant and uninhabited Pianosa and some main rocks amongst which Il Cretaccio and La Vecchia.
San Nicola and San Domino are the isles living centres. Human presence is testified since the Neolithic Age. The Benedictine monk arrived in San Nicola, historically the most important isle, around the year one thousand. They meant to keep the cult of the Madonna della Protezione, they built the Santa Maria a Mare fortified abbey (which was passed over to the Cistercians), that dominates the landscape with its one thousand years of history and architecture. Around 1760 the abbey history abruptly changed: it was used as a penal colony by the king of Naples; a function it kept till the Second World War. The origins of the church of Santa Maria delle Tremiti is in a chapel of the IV century, which was re-built in 1054. The island of San Domino was called the "paradise orchard" by the monks. As a matter of fact, it is characterized by luxurious pine trees and Mediterranean vegetation; on its coast are extraordinary beaches and little coves like Cala Martano, Punta di Pigno, Punta dell'Elefante, the Cala delle Roselle and the Grotta delle Viole, of the Bue Marino up to the Cala Rossa and the Cala degli Inglesi. It is an island which never stops amazing. Even though it is uninhabited, the Capraia isle in fascinating, too.