ijen

Since national geografic mentioned the electric-blue flame of Ijen, tourist numbers increased. The phenomenon has occurred for a long time, but before hand there was no midnight hiking. A two-hour hike is required to reach the rim of the crater, followed by a 45-minute hike down to the bank of the crater. The blue fire is ignited sulphuric gas, which emerges from cracks at temperatures up to 600 degrees Celsius (1,112 degrees Fahrenheit).
The flames can be up to five meters (16 feet) high; some of the gas condenses to liquid and is still ignited. It is the largest blue flame area in the world and local people refer to it as ‘Blue Fire’