The otherworldly red river © Oscar Diez Martinez/Minden Pictures
The Rio Tinto, in Andalusia, Spain, gets its strange color from dissolving iron deposits in the highly acidic water. Beginning more than 5,000 years ago, this area was mined for gold, silver, and other treasures. And archeological evidence suggests that about 3,000 years ago this may have been the site of King Solomon’s legendary mines. Scientists believe that pollution from the mines contributed to the extreme ecological conditions we see in the Rio Tinto today.