The smoking crater of the Bromo Volcano (Java, Indonesia)
The smoking crater shaft is surrounded by steep and very unstable volcanic ash, and frequent loud explosions can be heard from deep in the shaft. Local people throw offerings into the crater.
I heard that during some religious events, locals people defy death and dance on the steep slope just above the shaft. Footsteps from those events can be seen.
For more information about Bromo Volcano, read en.wikipedia.org/wiki/Mount_Bromo