Kelimutu is a volcano, close to the small town of Moni in central Flores Island of Indonesia. The volcano contains three striking summit crater lakes of varying colors. Tiwu Ata Mbupu (Lake of Old People) is usually 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 ( Enchanted Lake) are separated by a shared crater wall and are typically green or red respectively. The lake colors vary on a periodic basis. Subaqueous fumaroles are the probable cause of active upwelling that occurs at the two eastern lakes.
The visitor is never quite sure what color the lakes will be when they reach the top as they vary significantly. Unlike other crater lakes where the color variation can be predicted, this is not the case with these three lakes. The colors you see here are blue, green and black (and they predominate) yet the lakes also change to white, red and blue too.