Kawa Ijen

The Ijen volcano complex is a group of stratovolcanoes, in East Java, Indonesia. The volcano has a one-kilometer-wide turquoise-colored acid crater lake. The lake is the site of a labor-intensive sulfur mining operation, in which sulfur-laden baskets are carried by hand from the crater floor. The lake has the same acid content as a car battery. Flaming molten sulfur flows inside the volcanic crater. Sulfur will melt at just above 100 C, but the temperatures in the crater do not get high enough for spontaneous combustion - the fires are lit by the miner's dripping torches.