Deviation Actions
Description
Ijen Crater has a one-kilometer-wide turquoise-colored acid crater lake. Which now more famous after BBC television documentary Human Planet and National Geographic mention it. 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.
Many other post-caldera cones and craters are located within the caldera or along its rim. The largest concentration of post-caldera cones forms an east/west-trending zone across the southern side of the caldera. The active crater at Kawah Ijen has an equivalent radius of 361 metres (1,184 ft), a surface of 0.41 square kilometres (0.16 sq mi). It is 200 metres (660 ft) deep and has a volume of 36 cubic hectometres (29,000 acre·ft).
The lake is recognised as the largest highly acidic crater lake in the world, and since it is also a source for the river Banyupahit, resulting in highly acidic and metal-polluted water, it has a significant detrimental effect on the downstream river ecosystem. In 2008, explorer George Kourounis took a small rubber boat out onto the acid lake to measure its acidity. The pH of the water in the crater was measured to be 0.5 due to sulfuric acid.