Arjuno-Welirang, Volcanic complex in East Java, Indonesia

Arjuno-Welirang is a twin stratovolcano: Arjuno rises to 3,339 m on the same ridge as Welirang, and the summit lacks vegetation. The upper slopes are dark greyish-blue and taper to a rounded, slightly uneven top, while the midsection and base are green, cut by deep, branching gullies and ridges. Fumaroles with sulfur deposits occur in several locations on Welirang.

Arjuno-Welirang is a twin stratovolcano: Arjuno and Welirang share one ridge, and the complex sits within the older volcanoes Ringgit to the east and Linting to the south. About ten pyroclastic cones lie along a 6 km line between the two summits. Recorded eruptions came in 1950, measured VEI 2, and again in 1952 at VEI 0.

The mountain draws its name from Arjuna, a hero in the ancient Hindu epic Mahabharata, showing how Javanese people link their sacred stories to the landscape around them. Local communities view this place as part of their spiritual geography.

Official trailheads are at Sumber Brantas (Batu), Tretes, Tambaksari (Purwodadi) and Lawang; the Tretes route is the steepest. The summit, Ogal Agil, has no crater, so white smoke seen there comes from Welirang. Entry posts operate daily 08:00–16:00 WIB.

The mountain slopes contain the source of the Brantas River, the second longest river in Java and crucial to the region. The slopes support four distinct forest zones, each with its own plant communities adapted to different elevations.