Revelation 9:2

John saw smoke rising from the shaft leading to an underground chamber. The smoke probably symbolizes the terribleness of the place from which the locusts emerge (cf. Ephesians 2:2). In Revelation smoke usually relates to judgment, doom, and torment (Revelation 9:17-18; Revelation 18:9; Revelation 19:3), though it also has connections with holy things (Revelation 8:4; Revelation 15:8). The context specifies a negative connotation here (cf. Genesis 19:28; Exodus 19:18). What John saw resembled smoke billowing out of an active volcano.