I've been there and it's wonderful.
Ostia is a quarter of Rome and is reachable in about 20 minutes from the center of the City. It is one of Lazio's major attractions, particularly interesting to those who can't make it to Pompeii. Italy might be a Catholic country, but you won't detect any religious conservatism in the skimpy bikinis on display here. There's a carnival atmosphere, with dance halls, cinemas, and pizzerias. The Lido is set off best at Castelfusano, against a backdrop of pinewoods. This stretch of shoreline is referred to as the ROMAN RIVIERA. Sun, sea, beach and culture at few kilometers from the center of Rome! This is the roman sea.