Solfatara

Solfatara is a shallow volcanic crater at Pozzuoli, near Naples, part of the Phlegraean Fields volcanic area. It is a dormant volcano, which still emits jets of steam with sulfurous fumes. The name comes from the Latin, Sulpha terra, "land of sulfur", or "sulfur earth". It was formed around 4000 years ago and last erupted in 1198 with what was probably a phreatic eruption – an explosive steam-driven eruption caused when groundwater interacts with magma. The crater floor was a popular tourist attraction until 2017, as it has many fumaroles and mud pools. The area is well known for its bradyseism. The vapours had been used for medical purposes since Roman times.

This volcano is where the thermoacidophilic archaeon Sulfolobus solfataricus was first isolated. The archaeon is named for the volcano, as most species of the genus Sulfolobus are named for the area where they are first isolated.