Crater lakes (also called volcanic lakes or calderas) are large depressions formed in a volcano after an eruption. They may also be formed at sites of meteor crashes or man-made implosions. As rain falls the deep impressions are filled with water resulting in some incredible sites of nature in an isolated locale. The presence of minerals in the lakes can affect the colour. Dark blues and indigos to turquoise and bright greens.
On the island of Flores in Indonesia is the volcano Kelimutu. This volcano is of interest as it contains, in the same volcanic crest, not one but three crater lakes. An added phenomenon is that each of the lakes are different colours. Over time they may also change, most likely due to volcanic gases and minerals. Greens, browns, blues and even red have been seen in these unique lakes.
This area of Flores is an draw for many a traveler. From the small town of Moni, interested parties can take a 12 km/7.5 mi hike to the volcano to see the lakes on a dedicated (and safe) trail. The most popular time to visit is very early morning to catch the sun rise and bring about the day. Midday is when the colours of the lakes are at their peak. Additionally one can hike from the parking lot near the base of mountain. Further information can be found here.