Kawah Ijen is an active volcanic crater in Banyuwangi, East Java, Indonesia, famous for its electric-blue 'blue fire' visible only in darkness and for holding one of the world's largest and most acidic turquoise crater lakes. The blue flames come from sulfuric gases that ignite on contact with air at around 600 degrees Celsius, so you must reach the crater rim while it is still pitch dark to see them. It is also a working sulfur mine where laborers still haul chunks of sulfur by hand.
Blue fire (blue flame): a rare phenomenon of glowing blue flames, visible only in the dark before dawn
Turquoise acid crater lake: one of the world's largest lakes with a pH near zero, stunning at first light from the rim
Sunrise and sea of clouds from the crater rim after the pre-dawn blue-fire descent
Sulfur miners at work: a chance to witness laborers carrying heavy sulfur loads up and down the crater
Roughly 3 km night trek from the Paltuding base camp to the rim, about 1.5 to 2 hours one way
Good to know
SafetyThe crater has some of the highest accessible concentrations of sulfur-dioxide gas anywhere. A proper gas mask is effectively mandatory when descending to the blue-fire vents; a surgical mask offers no protection. If the wind shifts and gas engulfs you, move upwind immediately as it severely irritates eyes and throat.
SafetyThe lake water is as acidic as battery acid and causes severe chemical burns on contact. The blue-fire descent is a dark, slippery, steep scramble with real fall and disorientation risk, so hiring a local guide is advisable for first-timers or night hikes (verify current rules).
RulesSince 2024, visitors have at times been required to present a medical certificate confirming no history of heart or respiratory conditions, and people with asthma may be barred from the climb. Confirm entry rules and required documents before you go.
SeasonThe blue fire can be temporarily switched off for natural or maintenance reasons (it was extinguished during sulfur-pipe repairs in early 2026 and reopened on 26 February 2026). Sightings are never guaranteed, so check current status and be ready to enjoy the lake and sunrise even if the flames are dark.
CautionThe man-pulled 'trolley (human taxi)' to the summit is quoted at widely varying prices (often around 800,000 to 1,200,000 IDR round trip), so always negotiate and confirm terms (round trip vs one way, number of people) in advance. Gas-mask rental, jeep, and shuttle fares are also negotiable, so know typical rates first.
MannersAsk permission before photographing miners and offer a small tip (around 20,000 IDR); avoid candid shots or 'poverty tourism' style behavior, and yield the narrow trail to loaded miners.
Practical info
Generally open from around 02:00 to noon, and closed on the first Friday of each month. Foreigner entry is roughly 100,000 IDR on weekdays and 150,000 IDR on weekends, with gas-mask rental around 45,000 IDR, but confirm all latest figures. The dry season (April to October) offers clear skies and safer trails; the rainy season brings fog, slippery paths, and sudden closures. Bring a headlamp, grippy hiking shoes, and a warm outer layer.
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