At volcano-rich Java, Kawah Ijen distinguishes itself from other volcanoes by a crater lake with an extremely high acid-level. Constant rising sulphur fumes are melted and guided outside by pipelines. Consolidated as yellow substance, porters are hauling the sulphur-containing chunks up the rim of the crater and from there downwards off the volcano to a weigh station. Making two trips a day this exhausting and unwholesome work yields a porter a poor income.