Lake in Indonesia that has the same pH value as car battery acid

Kawah Ijen is one of the most incredible and surreal places.It's the site of a labor intensive sulfur mining operation where miners collect and carry huge loads of pure sulfur up from the crater floor along a steep, rocky path amid clouds of sulfur dioxide gas, all for the equivalent of about ten dollars a day.
It is also home to the largest lake of sulfuric acid in the world.The ph of the lake water is 0.5, similar to the strength of car battery acid.