Mount Kelimutu is an active volcano. Inside the huge crater complex are three lakes filled with water of different colors, respectively burgundy red, pale green and dark blue.
The lakes of Kelimutu have changed in color, a phenomenon caused by the geological and chemical processes in the bottom and walls of the lakes. It could also have resulted from changes in the bacteria and microorganism populations due to changes in temperature.
Another theory proposed by village elders, is that there has actually been no change at all, but that the effect is due to optical illusions.