Ijen volcano complex

A complex of stratovolcanoes on the border of Banyuwangi and Bondowoso regencies in East Java, Ijen is best known for the turquoise acidic crater lake and the phenomenon of blue sulfuric flames visible during the predawn hours at the crater rim. Miners traditionally descend into the crater to extract elemental sulfur by hand, carrying loads of up to 90 kilograms along narrow paths. The 2.5-hour night hike to the crater rim is one of East Java's most demanding and visually striking trekking experiences.