"The Kawah Putih site was opened to visitors in 1987. The lake is 2,430m (7970 ft) above sea level, so the local climate is often quite chilly (temperatures are frequently around 10 degrees celsius). This makes a brisk change from the humidity of the north Java plain and the capital city of Jakarta. Kawah Putih is a sizeable highly acid lake (pH 0.5-1.3) which changes colour from bluish to whitish green, or brown, depending on the concentration of sulfur and the temperature or the oxidation state. The sand and rocks surrounding the lake have been also leached into whitish colours through interaction with the acidic lake waters (with possible mineral precipitation as well)."
I can only imagine how beautiful this is in real life as it is in the photo. wow