Mythology & Beliefs: Avernus In Greek and Roman Mythology, Avernus was the Infernal regions; name derived from small vaporous lake
near Vesuvius which was fabled to kill birds and vegetation.
Avernus in Wikipedia
Avernus was an ancient name for a crater near Cumae (Cuma),
Italy, in the Region of Campania west of Naples. It is
approximately 2 miles in circumference. Within the crater is
Lake Avernus (Lago d'Averno). Avernus was believed to be
the entrance to the underworld, and is portrayed as such in
the Aeneid of Virgil. The name is coming from the greek word
"αερνος", meaning without birds, because according to
tradition all birds flying over the lake were destined to fall
dead. In later times, the word was simply an alternate name
for the underworld...