The bubbling emerald green crater lake of East Java’s Kawah Ijen is a beautiful sight, save for its toxicity. The lake is a potent acidic cocktail of hydrogen chloride, sulphuric acid, aluminium sulphate and iron sulphate. From various vents in the volcanic crater, fumaroles emitting sulphurous vapours (mainly sulphur dioxide) are channeled so that solidified lemon yellow sulphur can be recovered and sold. Twice daily workers chip off large hunks, load up their bamboo baskets to 70 kg and manually climb out of the steep crater and down to the weighing station. In this highly corrosive environment the workers use only a damp rag to cover their mouth to slow the degradation of their lungs and teeth from inhalation of the toxic gas.