It is quite possible - even if you do not rent a car. There are two options for this. The first is from Rome by public transport to reach the coast, take a dip in the sea, sunbathe, relax in the local cafe near the beach and return the same way to the hotel in Rome. The second is to be located somewhere closer to the sea, and to Rome to go on excursions and just take a walk.

In the first case, you need a route: the line In the Roman metro (the initial station of Rebibbia, the final one is Laurennina), go in the direction of Laurennina to station Basillica S.Paolo. Please note that there is only one station from Line A to Line B - Termini, the Roman railway station.

It is most convenient to take a pass for all types of transport (~ 4 EUR / day). At the Basillica S.Paolo station, proceed to another path by the sign Lido di Ostia. 15 minutes. on the train, and the next after stopping Ostia-Antica (Roman Pompeii) is yours. Exit to the station square and to the left of the station for 5 - 6 minutes. reach the waterfront by the sea. There are a lot of paid private beaches here (about 20 EUR per day from one holiday-maker), and there are free ones.

If the option to stay closer to the sea seems to be more convenient, pay attention to the coast of the Tyrrhenian Sea: Tuscany and the so-called Odysseus coast (or Riviera di Ulysses). Or a place Terracina, from where for 15 minutes. take the bus to Monte San Biagio and then an hour by train to Rome (Termini)