Phlegraean Fields

Phlegraean Fields is a volcanic caldera roughly 13 kilometers wide in the Metropolitan City of Naples, comprising 24 craters, fumaroles, hot springs, and mud pools. The terrain lies west of the city and extends from the mainland to offshore islands, with active geothermal activity producing visible steam clouds and discolored soils at many points.

A major eruption roughly 39,280 years ago ejected enormous volumes of magma and shaped the current caldera, with ash reaching large parts of Europe. Smaller eruptions have occurred since then, including one in 1538 that formed Monte Nuovo.

Fumaroles and thermal springs have drawn visitors for centuries who experience natural phenomena in the sulfurous vapors and bubbling mud pools. Many sites throughout the region carry names from ancient mythology, which still recall the long relationship between people and the volcanic landscape.

The area is accessible by car or public transport from Naples, with several craters and thermal springs reachable by walking paths. Visitors should watch for uneven ground and keep a safe distance from craters with active fumarole activity.

The Vesuvius Observatory monitors the region continuously with multiple seismic stations recording ground movements and gas emissions. In September 2023, the area experienced its strongest earthquake in 40 years, measuring 4.2 on the Richter scale.