Volcanic lake near Cumae, in Campania, which the Romans regarded as the entrance to the world of the dead. In Book VI the name also serves for the underworld itself, and the Sibyl warns that going down to Avernus is easy and coming back is the task. Aeneas crosses it with the golden bough, passes the river of Charon and reaches Elysium, where his father shows him the future Romans.
Where It Appears
Quotes
You will reach safely the harbor of Avernus that you desire. There will be only one who, lost in the current, he will search for; a single head will be given for many.
But first enter the infernal dwellings of Dis and, through the depths of Avernus, come to meet me, son. The impious Tartarus does not hold me back, nor do the sad shadows; I dwell in the pleasant assemblies of the pious and in Elysium. There, with the blood of many black cattle, the chaste Sibyl will take you.
Easy is the descent to Avernus; night and day the door of dark Dis stands open; but to turn back and escape to the breezes above, this is the task, this is the labor.