Any nudist activity in Rome?
While we haven't been to the nude beach, we have been to Ostia Antica. You can get to the Piramide station on the subway blue line as well, so you don't have to take the bus. Read up on the train and subway rules in Rome and remember to validate your ticket in one of the yellow machines. Pyramide was the only station where we were asked to show our tickets when exiting and it is a good thing they had been validated. Otherwise it is a 50 Euro fine. You could theoretically keep using the same ticket forever if it isn't validated, just don't get caught.
Update: it looks like the subway has newer entrances now that automatically validate your ticket (so it's been 12 years since we were in Rome). You still need to manually do it on busses and (as of 12 years ago) on the train to Ostia Antica/beaches.