Rio Tinto, Spain
The extremely polluted Rio Tinto can be found in Spain. The river runs red with Burdundy’s blood (a little Anchorman reference there). But the area was mined heavily mine, but the runoff of which had greatly polluted the lake. and river nearby. This pollution, in turn, is grossly acidic. Avoid.
Unfortunately, it’s one of the most dangerous vacation spots in the world.