It's a scientific fact that volcanoes cause crazy-a$$ natural phenomena...case in point: Kelimutu in Indonesia, a volcano and National Park. At the summit of the volcano, within the crater, are three lakes. But lakes in volcanic craters aren't that rare-- just check out Crater Lake National Park. What makes the beautiful lakes at Kelimutu National Park so special is that they're always changing colors, from shades of black to red to green to blue and back, totally independently of one another.
The first lake, Tiwu Ata Bupu (which translates roughly to "The Lake of Old People") is usually a shade of blue. The other two are closer together; Tiwu Ko'o Fai Nuwa Muri ("The Lake of Young Men and Maidens") generally appears to have a greenish hue, while Tiwu Ata Polo ("Enchanted Lake" or "Bewitched Lake", depending on your mood) is often red. The most popular theory on the cause of the color changing is that various minerals in each of the lakes reacts differently with the gas coming from the volcanic activity below the surface. So basically, they're like mood rings for the local geothermal activity.
They were first noted by a Dutch military commander in 1915, but it wasn't until the late 1920's that the lakes started to gain local fame and attention. Today, the lakes (and the National Park itself) are a popular tourist destination-- in fact, all three lakes appear on the Indonesian 5,000 rupiah banknote. There aren't many places in the world that you can visit more than once and see something totally different every time...plus, did I mention that they're totally stunning?
Header via Wikimedia Commons