Kawah Ijen is a composite volcano located at the easternmost part of Java island in Indonesia and hosts the largest natural acidic lake in the world. detail info please cek here Bulletin of Volcanology   

Kawah Ijen (2386 m) is a composite volcano located within the Pleistocene Ijen Caldera, at the easternmost part of Java island, in Indonesia (Fig. 1). The visible superficial manifestations of the hydrothermal system of Kawah Ijen’s activity consist of the world’s largest hyperacidic lake on Earth (V = 27 * 10 6 m 3T > 30 C, pH < 0.3), a few thermal discharges and crater fumaroles (Delmelle et al. 2000) which produce significant amounts of native sulfur. Specific dynamics and seismicity are triggered by the hydrothermal activity. The most recent magmatic eruption of the volcano took place in 1817, but frequent phreatic and geyser-like activity have occurred since that time (Global Volcanism Program: http://www.volcano.si.edu).

Get There

The Ijen Plateau can be reached through Bondowoso from either the northern or the southern coast. It is closer to Banyuwangi,

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