Mount Batur (Indonesian: Gunung Batur; Balinese: ᬕᬸᬦᬸᬂᬩᬢᬸᬃ, romanized: gunung batuŕ) is an active volcano located at the center of two concentric calderas northwest of Mount Agung on the island of Bali, Indonesia. The southeast side of the larger 10×13 km caldera contains a caldera lake. Both the larger caldera, and a smaller 7.5 km caldera were formed by a collapse of the magma chamber, the first larger collapse taking place about 29,300 years ago, and the second inner caldera collapsing about 20,150 years ago. Another estimate of the inner caldera's formation date, formed during the emplacement of the Bali (or Ubud) ignimbrite, has been dated at about 23,670 and 28,500 years ago. The first documented eruption was in 1804 and the most recent was in 2000.
