They are an archipelago, a protected sea park in the National Park of Gargano. It is placed 21 km north of the headland of Gargano with a typical scenery of rocky calcareous coasts, bays, cliffs, stacks and sea-caves. The islands S. Nicola, San Domino, Capraia, the most remote and isolated Pianosa and other rocks, the bigger one is the Cretaccio, form the archipelago. From a naturalist point of view, the sea depths are very important, thanks to the clearness of the water, it is possible to see in a few metres depth, coloured sponges, colourful fan-shaped annelids, sea urchins and starfishes. At a higher depth, it is easy to admire blooming multicoloured sea fans close to groupers, morays, conger-eels, crawfishes. The Tremiti sea depths offer one of the most exciting divings into the Mediterranean sea. In the archipelago the populated islands are San Domino and San Nicola; in 1045 on the San Nicola Island, historical, religious and administrative centre of the Tremiti Islands, the Benedictine monks of Montecassino built the Abbey of Santa Maria a Mare. It was forti?ed by Charles of Anjou and in 1300 it suffered the attack of the pirates. They destroyed the fortress and killed the monks. The Abbey of Santa Maria is a beautiful harmony of Byzantine and Romanesque art in the typical style of Benedictines and Cistercians.