The Phlegraean Fields (Campi Flegrei)

This is an area west of Naples, which is on a caldera about 13km wide. It is bordered by the Posillipo Hill in the east, Quarto in the north, Cuma and Monte di Procida in the west and the Gulf of Pozzuoli to the south. The islands of Ischia and Procida are also close to the area of the Phlegraean Fields, which takes its name from the Greek word for burning. The volcanic area, close to Vesuvius, are prone to bradyseism, a natural phenomena in which volcanic activity causes the ground to move up or down. In the case of the Roman towns of Baia, Miseno and Puteoli, the ground subsided, leaving them submerged in the sea. 
 
The area is extremely rich in Greek and Roman history. It is the site of the ancient fortified town of Cumae, founded by settlers from Chalcis in 730 BC and was one of the first Greek colonies in Italy. Dicaearchia was founded in the sixth century and later became Roman Puteoli, or modern-day Pozzuoli. Cumae was conquered in the fifth century BC by the Romans and by the time of Augustus, Puteoli become one of the most important ports of the Roman empire.

Today, the most important Roman sites of the Phlegraean Fields are underwater. They are:

• Portus Julius
• Pisonian Villa
• Protiro Villa
• Fish Pools