Glacier of Blood

Blood Falls is located in at the edge of the McMurdo Dry Valleys in Antarctica. The Dry Valleys are one of the few places in Antarctica that have no ice or snow on them. But that's a topic for another post. Blood Falls (or Glacier of Blood as I like to call it) is located at the tongue of the Taylor Glacier.
It is fucking awesome! Originally it was though to be caused by a wound in the glacier red algae. That's a good guess for 1911. Really, the water is hypersaline, iron-rich, seawater from a subglacial pool. It is unknown how large this pool is, but the water was isolated from the Antarctic Ocean for 5 million years. The iron in the water oxidizes in the presence of oxygen, giving it its evil blood color. Though there's almost no oxygen in the trapped seawater, there are still bacteria living in it.

Picture from Discover Magazine Article:

Hi-res image from the United States Antarctic Program (click to embiggen):