Indonesia, volcano Ijen, which 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 work is low-paid and very onerous. Workers earn around $5.50 per day and once out of the crater, still need to carry their loads of sulfur chunks about three kilometers to the nearby Pultuding Valley to get paid.
Roman Shalenkin photography.