an active volcano on the eastern part of the island of Java in Indonesia. With an elevation of 3,676 m, Semeru is the highest point on the island. It has several craters; the diameter of the active crater is 500–650 m. Depths range to 220 m. Since 1818, 55 eruptions have been recorded, with the most recent in 1972. Semeru is composed of basalts and andesites. Dense tropical forests grow on the slopes.