The lake
| Feature | Figure |
|---|---|
| Crater width | 722 m |
| Crater depth | 200 m |
| Lake width | About 1 km |
| Lake pH, middle (July 2008) | 0.13 |
| Blue fire gas temperature | Up to 600 °C |
| Blue flame height | Up to 5 m |
| Ijen caldera width | About 20 km |
The water drains into the Banyupahit river, and its acid and metals harm the ecosystems downstream. From the rim at dawn the colour is clearest; at night you see the blue fire at the lake edge instead.
The sulphur mine
| Fact | Figure |
|---|---|
| Load per trip | 75–90 kg |
| Climb from lake to rim | 300 m |
| Walk down to the weighing post | 3 km |
| Trips a day, most miners | 2 |
| Miners | About 200 |
| Sulphur taken per day | About 14 tonnes |
Gas venting at the lake edge runs through ceramic pipes and condenses into molten sulphur, which sets into the yellow blocks the miners break off. The 14 tonnes they take each day is about a fifth of what is deposited. Miners work with little protection and suffer breathing problems.
Night tours from Banyuwangi reach the lake edge before dawn.
On film
The mine has been filmed for the 1991 IMAX film Ring of Fire, the BBC series Human Planet and Michael Glawogger’s Workingman’s Death.
Before you go down
The crater floor is where the gas vents. The park advises people with asthma, heart disease or breathing disorders against the hike; see the health rules. The crater is shut on the clean-up Fridays.
