High Quality Content by WIKIPEDIA articles! Campi Flegrei, also known as the Phlegraean Fields is a large 13 kilometres (8.1 mi) wide caldera situated to the west of Naples, Italy. It was declared a regional park in 2003. Lying mostly underwater, the area comprises 24 craters and volcanic edifices. Hydrothermal activity can be observed at Lucrino, Agnano and the town of Pozzuoli. There are also effusive gaseous manifestations in the Solfatara crater, which is known as the mythological home of the Roman god of fire, Vulcan. The area also features bradyseismic phenomena, which are most evident at the temple of Serapis in Pozzuoli.