Mount Kelimutu is a volcano, near to the small town of Moni approximately 50 km to the east of Ende, Indonesia in central Flores Island of Indonesia.
The volcano has three stunning summit crater lakes of different colors. Tiwu Ata Mbupu (Lake of Old People) is generally blue and is the westernmost of the three lakes. The other two lakes, Tiwu Nuwa Muri Koo Fai (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched or Enchanted Lake) are split up by a shared crater wall and are usually green or red respectively. The lake colors differ on a periodic basis. Subaqueous fumaroles are the possible reason for active upwelling that happens at the two eastern lakes.
Within the last three to five years, the lakes of Kelimutu have changed in color, a happening due to the geological as well as chemical processes in the bottom part and wall surfaces of the lakes. It could actually also have caused by changes in the bacteria and microorganism populations as a result of changes in temperature.
The lakes are actually a source of minor phreatic eruptions in old time. The peak of the compound 1639-m-high Kelimutu volcano is elongated two km in a WNW-ESE direction; the older cones of Kelido and Kelibara can be found respectively three km to the north and two km to the south. The beautiful lakes are a well known tourist destination.