Ijen Crater

The hike starts at 1am in darkness. Torches bob up the volcanic trail in a chain of light. At the crater rim, sulphurous fumes roll upward and the air thickens. Then you descend into the crater itself — and there, in the toxic murk, blue flames dance across the rocks where sulphuric gas ignites on contact with air. Miners haul 80-kilo baskets of yellow sulphur up the crater wall on their shoulders, their faces wrapped in rags. By dawn, the turquoise acid lake below reflects a sky turning gold.

Kawah Ijen is an active volcanic crater in the Ijen volcano complex, East Java, at 2,386 metres. The crater contains the world's largest highly acidic lake — approximately one kilometre wide with a pH of 0.5. The famous blue fire phenomenon is caused by combustion of sulphuric gases emerging from fumaroles at temperatures above 600°C, visible only in darkness. An active sulphur mining operation employs local miners who carry loads of 75-90kg up a 300-metre climb from the crater floor. The trek from Paltuding base camp to the crater rim takes approximately 90 minutes; the descent to the crater floor adds 45 minutes on steep, slippery terrain. Gas masks are recommended due to SO₂ concentrations that regularly exceed safe levels. The nearest town is Banyuwangi, gateway to the Ijen Geopark and the ferry crossing to Bali.