This is the marine portion of the huge Porto Conte park ecosystem, added in 2002. The protected area of Capo Caccia - Piana Island falls within the territory of Alghero and includes Porto Conte bay and the stretch from Punta Giglio to Capo Caccia: a priceless natural heritage, embellished by the fossil-rich limestone and rare plants growing on the cliffs. You can visit nature and archaeological sites with trekking and caving itineraries, such as Le Prigionette, a forest with white donkeys, Giara ponies and deer, or - on permission - the Grotta Verde, where you can find traces from seven thousand years ago, perhaps intended for the dead or as grave goods, including human fossils, ceramic items and graffiti. If you're mad about archaeology, in the park don't miss the Nuraghic complexes of Palmavera and Sant'Imbenia and the Roman remains: Villa di sant’Imbenia and the bridge over the Calich.