Lake Ijen ( East Java )
The lake is 200 meters deep and contains about 36 million cubic meters of steaming acid water, shrouded in a smelling swirling sulfur cloud. Also known as the world's largest acidic volcanic crater
The
Ijen volcano complex is a group of
stratovolcanoes in the
Banyuwangi Regency of
East Java,
Indonesia. It is inside a larger
caldera Ijen, which is about 20 kilometers wide. The Gunung Merapi stratovolcano is the highest point of that complex. The name "Gunung Merapi" means "mountain of fire" in the Indonesian language (api being "fire");
Mount Merapi in central
Java and
Marapi in Sumatra have the same etymology.
West of Gunung Merapi is the Ijen volcano, which has a one-kilometer-wide turquoise-colored acidic
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 paid well considering the cost of living in the area, but is very onerous.
[1] Workers earn around
Rp 50,000 - 75,000 ($5.50-$8.30) 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.
[2]
Many other post-caldera cones and craters are located within the caldera or along its rim. The largest concentration of post-caldera cones run east-west across the southern side of the caldera. The active crater at Kawah Ijen has a diameter of 722 metres (2,369 ft) and a surface area 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.
[3] It is also a source for the river Banyupahit, resulting in highly acidic and metal-enriched river water which has a significant detrimental effect on the downstream river ecosystem.
[4] 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