Between Livorno and La Spezia there's a huge 100 km long beach. It has several names: Tuscan Riviera, Versilia, or Etruscan Coast. If you are traveling to Italy by car, it's quite convenient to visit this place as it is located near the highway A12. We visited the beach in Marina di Massa. Most beaches here are paid (about 5 euros), but there are also several free beaches. We swam near the pier, which is indicated on the Google Map below, and which is the most interesting place in the town.
There's a park of rabbits in Marina di Massa, but we found this information later.
Getting there: The nearest airport is in Pisa. There are transfers to large seaside resorts from the airport. There's a railroad Pisa - La Spezia - Genoa along the coast, the nearest station is Massa Centro in 4 kilometers from the pier. From the station (FS Massa) to the pier (Piazza Betti) you can get by buses ##60, 62, 64. Check out their schedule and route map here.
Buses of Vaibus also run in the region from the side of Lucca. They run around the coast so you can get to any town. Check out the map and timetable of routes in the region here.