Although topless sunbathing in Italy is common, there are few nude beaches in Italy. The following are considered "official" nude beaches.
You can reach Capocotta Beach, located south of Rome, via public transportation. Make sure you stay in the section designated for nude sunbathing.
Costa Verde Beach, in southwest Sardinia, has a section designated for nudists.
To reach Guvano Beach, take the train to the Corniglia station. From there, you follow the path to Vernazza and turn onto the path that leads towards the surf.
Costa dei Barbari, in Trieste, is an official nude beach. If you're in the area, you should also visit Filtri di Aurisina, a nude beach between Trieste and Duino. The nude portion of the beach is shielded by woods.
