Kelimutu Coloured Lakes

Kelimutu is a passively degassing stratovolcano capped by three crater lakes containing exotic fluids and whose physico-chemical expressions have changed dramatically through the years. The volcano is located on Flores, an island along the Lesser Sunda islands chain of Indonesia. An early description of Kelimutu was provided by the French naturalist LeRoux, who mentions it in his travel log of eastern Indonesia in 1896. A more comprehensive geologic and topographic survey was performed in the 1920's by the Dutch colonial geologist Kemmerling, who traveled through Flores on horseback and early motor vehicle. Since 1929 no publicly reported systematic survey of Flores has been done using modern techniques.
Kelimutu Crater Lakes

Three crater lakes are located on the eastern summit of Kelimutu. Each of the lakes has a distinctive physical structure, a unique geochemical and hydrothermal regime, and a particular historical sequence of color changes controlled by changes in physico-chemical conditions.

Tiwu Ata Polo the "enchanted lake", lies on the southeastern side of the volcanic peak. A thermal plume in the northwest part of the lake indicates underlying subaerial fumarolic or hydrothermal activity. A white froth is present on the lake's surface around the plume when the convective activity momentarily increases. Rock debris is often carried into Tiwu Ata Polo during rainstorms by water draining the volcano summit around the lake. Two peaks abutting the crater rim help stabilize the east and northeast crater wall, while further around to the southeast a dip suggests a possible one-time overflow outlet. Such an outlet would have fed the river Ria Mbuli, whose upland source is in that area.