The source of Antarctica's gruesome looking Blood Falls has finally been discovered putting an end to the mystery of where the red water came from.

At first it was thought some form of algae was discolouring the water, but that hypothesis was never verified.

Researchers from the University of Alaska Fairbanks have now concluded that the blood resembling liquid is iron-rich brine that comes from a more than million-year-old lake trapped beneath the Taylor Glacier.

The colour of the water can be attributed to oxidised iron in brine. It is the same process that gives iron a dark red colour when it rusts.

Researchers used radio echo sounding to detect the saltwater's path. They discovered that the water had taken close to 1.5 million years to finally reach Blood Falls as it made its way through fissures and channels within the glacier.

Blood Falls
The red liquid that resembles blood is iron-rich hyper saline water Wikimedia Commons

Water would normally freeze under such extreme cold conditions, but researchers say a combination of the heat given out during the freezing process and the lower freezing temperature of salt water allowed the lake's water to keep its form. The brine scrapes iron from the bedrock as it seeps through the ice to give it the colour red.

The research is published in the Journal of Glaciology.