Ancient Romans, such as Julius Caesar and Nero, used this region as their summer playgrounds. The two emperors built opulent summer villas and bathed in lavish spa complexes. Virgil also spent the last ten years of his life writing The Aeneid while living in this area. Book six of his work features the Phlegraean Fields as the real-life setting for Aeneas' journey into the underworld.
Lakes, grottoes, and temples can still be explored. And yet, since most short-term visitors opt to see Pompeii and before dashing off to the next Italian city, these sights tend to remain quiet, even desolate where exploration can be done without the crush of crowds.
If you have time to get dive certified, the best way to see the bubbling fumaroles and underwater Roman villas is with the Underwater Archeological Park of Baia.