One of the best sights in Indonesia (and there's a lot of good ones), Kawah Ijen is beautiful, dangerous, and also fascinating with its (seemingly) crazy sulfur mining operation. At night, as heat from the sulfur vents in the crater set liquid sulfur on fire, the flames burn blue. A sign at the entrance says it's temporarily closed because of safety concerns for both miners and tourists - and yet both continue to go everyday. A sign at the top of the crater tells visitors it's forbidden to hike down into the crater - more and more people are doing this everyday. It's one of those times you actually feel a little lucky that Indonesia's enforcement of such rules is well, pretty much nonexistent. At least of course until someone gets a bit unlucky.
You can read more about it here: http://en.wikipedia.org/wiki/Ijen .
Thanks to Sam for showing the way at night.
Music copyright the artists' labels:
M83 - Where the Boats Go
Explosions in the Sky - Last Known Surroundings, Let Me Back In