Semeru, or Mount Semeru (Indonesian: Gunung Semeru), is an active volcano in East Java, Indonesia. It is located in the subduction zone, where the Indo-Australia plate gets under the Eurasia plate . It is the highest mountain on the island of Java. This stratovolcano is also known as Mahameru, meaning ‘The Great Mountain.
Semeru’s eruptive history is extensive. Since 1818, at least 55 eruptions have been recorded (10 of which resulted in fatalities) consisting of both lava flows and pyroclastic flows. All historical eruptions have had a VEI of 2 or 3.
Semeru has been in a state of near-constant eruption from 1967 to the present. At times, small eruptions happen every 20 minutes or so.
Semeru is regularly climbed by tourists, usually starting from the village of Ranu Pane to the north, but though non-technical it can be dangerous. Soe Hok Gie, an Indonesian political activist of the 1960s died in 1969 from inhaling poisonous gases while hiking on Mount Semeru.
The name derived from the Hindu-Buddhist mythical mountain of Meru or Sumeru, the abode of gods.