Kawah ijen Indonesia

 Kawah Ijen harbours a large warm acidic crater lake and an active sulphur mine. Due to its easy accessibility, turqoise lake and unique sulphur mining operation, the crater is regularly visited by tourists. The last recorded magmatic eruption of Kawah Ijen was in 1817. The eruption displaced the crater lake and resulted in inundation of several villages along the drainage route. Phreatic eruptions have been reported in 1796, 1917, 1936, 1950, 1952, 1993, 1994, 1999, 2000 (also minor ash emission), 2001, 2002 (with minor ash emission), (?), 2011. The increasing frequency may reflect better reporting since the explosions are usually confined to the lake and cause little or no damage.
Various unverified sources claim that sudden gas release from the crater lake claimed the lives of numerous sulphur workers in 1976 (11-49) and 1989 (25). Such gas releases may occur with little warning in the future and probably represent the main hazard for visitors.