Kawah Ijen Blue Fire in Bromo and Ijen
Part of the Bromo and Ijen travel guide — see every topic in All Bromo and Ijen Guides.
Kawah Ijen is a 2,769-metre volcano in East Java whose crater holds a turquoise lake that is the largest highly acidic body of water on earth, with a pH close to that of battery acid. At vents on the crater's inner wall, sulphurous gases emerge at several hundred degrees, condense into molten sulphur, and ignite — producing flames that burn a deep electric blue and are visible only in the dark. Seeing them means climbing three kilometres in the middle of the night and then descending into the crater itself.
The climb
From the Paltuding post at around 1,850 metres, the trail climbs about three kilometres and 500 vertical metres to the crater rim, taking ninety minutes to two hours on a wide but steep and dusty path. Starting time is around one in the morning to reach the rim and descend before the blue fire fades with first light. From the rim, a rough scramble of twenty to thirty minutes drops several hundred metres down loose rock into the crater to the vents. The descent is the genuinely difficult part and there is no railing.
The gas
The vents emit sulphur dioxide and hydrogen sulphide at concentrations that are genuinely dangerous, and the wind shifts without warning. A proper respirator with acid-gas cartridges is essential, not a dust mask — guides supply them and it is worth checking the filter is not exhausted. If the gas comes over you, move immediately, upwind and upslope, and do not stop to photograph. Visitors have been hospitalised. People with asthma or any respiratory condition should think hard about the crater descent and can see the lake from the rim at dawn instead.
The miners
Sulphur is mined here by hand. Miners break solidified sulphur from ceramic pipes at the vents, load it into two baskets on a shoulder pole weighing seventy to ninety kilograms, and carry it up out of the crater and three kilometres down the mountain, often twice a day, for a few dollars a load. They work in the gas, mostly without adequate protection. Some now supplement their income by carrying tourists in wheeled carts. It is one of the harshest industrial jobs on earth and it is happening a metre from where you are standing.
Practicalities and the lake
Guides are compulsory and cost 100,000–250,000 rupiah plus the park entry, which is higher at weekends. Bring a head torch, warm layers, a scarf, and shoes with grip — the descent is loose rock in the dark. After the blue fire fades, stay for sunrise from the rim: the crater lake appears as an improbable milky turquoise, half a kilometre across, with the sulphur works steaming at its edge. Do not touch or swim in the lake. Ijen closes periodically for volcanic activity.
Kawah Ijen Blue Fire at a glance
| Height | 2,769 m; crater lake with pH near 0.5 |
|---|---|
| The climb | 3 km, ~500 m ascent, 1.5–2 h from Paltuding |
| Start | ~1am to see the flames before first light |
| Crater descent | 20–30 min scramble on loose rock, no railing |
| Essential | A proper acid-gas respirator, not a dust mask |
| The miners | 70–90 kg baskets, carried by hand, twice a day |