- PlaceThe volcanic lake Averna in the Phlegrean fields near NaplesLake Avernus (or Lago d'Averno in Italian) is a volcanic crater lake located in the Campania region of southern Italy, around 4 km (2.5 miles) northwest of Pozzuoli. It is near the volcanic field known as the Campi Flegrei and comprises part of the wider Campanian volcanic arc. The lake is roughly circular, measuring 2 km (1 mile) in circumference and 60 m (213 ft) deep.
Avernus was of major importance to the Romans, who considered it to be the entrance to Hades. It gained its name from the Greek word αορνος (originally αϝορνος) meaning "birdless", referring to the belief that birds flying over the lake would drop dead from the poisonous fumes that it emitted. The name Avernus was often used by Roman writers as a synonym for the underworld. In Virgil's Aeneid, Aeneas descends to the underworld through a cave near the lake.
It is unclear whether the lake actually was as deadly as its reputation held it to be – it certainly holds no fears for birds today – but it is possible that volcanic activity could have produced deadly fumes. Volcanically active crater lakes can be extremely dangerous places, as illustrated by the tragic example of Lake Nyos in Cameroon.
Despite the alleged dangers of the lake, the Romans were happy to settle its shores, on which villas and vineyards were established. The lake's personification, the deus Avernus, was worshiped in lakeside temples, and a large bathhouse was built on the eastern shore of the lake.
In 37 BC, the Roman general Marcus Vipsanius Agrippa converted the lake into a naval base named the Portus Julius after Julius Caesar. It was linked by a canal to a nearby lake (Lucrinus Lacus) and from there to the sea. The lake shore was also connected to the Greek colony of Cumae by an underground passage known as Cocceio's Cave (Grotta di Cocceio) which was 1 km (0.6 mile) long and wide enough to be used by chariots. This was the world's first major road tunnel; it remained usable until as recently as the 1940s.
This lake was called by Italian geographers, Lago di Tripergola.