The crescent-shaped crater lake of Batur, 1,031 meters above sea level, is seven and a half km long, with a maximum width of two and a half km, and a depth of between 65 and 70 meters. The western side is barren lava rock while the eastern side is lined with trees.

The average height of the huge outer rim is around 1,300 meters. Though there are no surface river outlets, the waters of the lake feed underground rivers, which emerge as holy springs in the southern part of the island.