Semeru

Semeru, also known as Mount Semeru, is the highest mountain on the Indonesian island of Java and one of the country’s most active volcanoes. It is located in East Java within the Bromo Tengger Semeru National Park and rises to an elevation of 3,676 meters above sea level. The volcano is a stratovolcano with a persistent summit crater that hosts a lava dome; the crater is commonly referred to as Jonggring Saloko.

Semeru has a long history of volcanic activity, including frequent eruptions, ash plumes, and gas emissions. Eruptions have intermittently disrupted nearby settlements and led to temporary closures of routes around the massif. In December 2021, a major eruption produced lethal pyroclastic flows and ash clouds, resulting in multiple fatalities and missing persons, underscoring the ongoing hazards associated with the peak.

As an active volcano, Semeru is closely monitored by Indonesian authorities, and aviation and local safety advisories are issued during periods of heightened activity. The surrounding region is protected as part of the national park, which also aims to preserve alpine habitats and volcanic landscapes.

Access and trekking: Semeru is a popular trekking destination. Typical routes begin from the village of Cemoro Lawang or from Ranu Pane, with ascent through the surrounding terrain toward the summit, usually over several days. Trekking is dependent on weather and volcanic activity, and visitors commonly obtain permits and guides as part of safety planning.