Kelimutu (pronounced [kəliˈmutu]) is a volcano close to the small town of Moni in central Flores island in Indonesia.

Oxidation-reduction status depends on the balance of volcanic gas input and rainfall rate,[4] and is thought to be mediated by the groundwater system in the volcano itself.

[1] Kelimutu's most recent eruption took place between June and July 1968, which included minor phreatic explositons.

The Tiwu Ko'o Fai Nuwa Muri has been a source of minor phreatic eruptions in historical time.

[14] The lakes' colors are determined by the volcanic gases, such as sulfur dioxide and hydrogen sulfide, released by the subaqueous fumaroles.

[13] Tiwu Ata Polo has been observed to fluctuate between red and green colors, controlled by sulfur concentrations and gas bubbling near the lakes shore.

[9] Tiwu Nua Muri Kooh Tai has yellow sulfur deposits, with lake water temperatures which indicate high fumarole activity during periods of increased gas output.

[9] Kelimutus lakes extremely low pH values increase chloride and sulfate concentrations, which further influence chemical composition.

[9] The upwelling of gases and water mixing are reposible for the boiling sounds heard around the lake, which is a telling sign of magmatic-hydrothermal interaction.

More recently, forest rangers have worked to develop better relations with nearby village communities and overall management has improved.

The area is said to have begun to attract attention after being noticed by a regional Dutch military commander, B. van Suchtelen in 1915 and became more well known after Y. Bouman wrote about the site in 1929.