In the stark, frozen landscape of Antarctica’s McMurdo Dry Valleys, a crimson waterfall known as Blood Falls has baffled scientists for over a century since its discovery in 1911.
Discovered by Australian geologist Thomas Griffith Taylor, this five-story-tall waterfall pours slowly from the Taylor Glacier, staining the ice below a deep, blood-red color. 
For decades, people thought the strange color came from red algae living in the water. It seemed like a reasonable explanation for such an unusual sight.
But the truth is far more interesting. The water flowing from the glacier is actually a hypersaline brine, saltier than seawater, that has been trapped beneath the ice for millions of years.
When this ancient, iron-rich water finally reaches the surface and comes into contact with oxygen for the first time, the iron oxidizes—it rusts. This is what gives the water its shocking red appearance.
What’s even more remarkable is what lies within this trapped water. Scientists have found a hidden ecosystem of microorganisms that have survived for ages in total darkness and without oxygen. 
These tiny lifeforms get their energy from chemical reactions involving iron and sulfate in the brine, a process called chemosynthesis. It’s a way of life completely independent of the sun.
Blood Falls serves as a natural laboratory, offering incredible insights into how life might survive in extreme, alien environments, like the subsurface oceans of Mars or Jupiter’s moon Europa.
Sources: National Geographic,