Kelimutu is a volcano, whose name is a combination of Keli meaning “mountain” and Mutu meaning “boiling”, meaning that the mountain is still active. Located on the top of the mountain are 3 volcanic lakes with the unique ability to change color due to the adjustment of oxidation levels of the lakes combined with iron and manganese content, helping these 3 lakes to change color continuously throughout the year.
Lake Tiwu Ata Mbupu (Lake of Old People) is usually blue in color and is located at the westernmost tip, 200 meters from the other two lakes. The other two lakes, Tiwu Ko’o Fai Nuwa Muri (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched or Enchanted Lake) are separated by a shared crater wall and are typically green or red respectively. According to a local legend, these two lakes are the resting places of dead souls, with Lake Tiwu Ata Polo being a place for evil spirits and Lake Tiwu Nuwa Muri Koo Fai said to be for young spirits. The remaining lake is said to be a place where older souls rest.
The color of the water in the three lakes changes after a certain period of time, with two adjacent lakes more often changing color than Tiwu Ata Mbupu Lake.
The entrance fee to the three lakes for foreigners is about IDR 150,000 from Monday to Saturday and IDR 225,000 on Sunday. When you come here to visit, remember to pay attention to your belongings because maybe the monkeys living in the mountains will steal them, as well as don’t get too close to the mouth of the lake to avoid accidents.
According to Wikipedia and theworldtravelguy.com