This red lake in France will amaze you. (see lots of images in link)
No supernatural mystery or plague here, just simple chemistry. The water acquire the red color from the presence of high concentration of iron oxide (ferrous Oxide) compounds dissolved by the corrosive salt (Sodium Chloride) in solution with water. Iron Oxide is commonly found on the surface of the earth as the red rocks and soils found in Mesas in the Grand Canyon, Navada. The color is indeed eerily mysterious lake.
Lovely pictures Ruth- I have the tab open on my browser so I will read it later - have to go to do some errands.