The eerie 'blood' waterfall that's been flowing from a glacier in Antarctica for centuries

An eerie, red-coloured stream has been flowing in Antarctica for centuries, which stands out so much against the icy white landscape that it looks like the glacier is bleeding. "Blood Falls" flows from the tongue of the 35-nautical-mile-long Taylor Glacier onto the ice-covered surface of West Lake Bonney in the Taylor Valley of the McMurdo Dry Valleys in the east of the southernmost continent.

First discovered over a century ago by Australian geologist Thomas Griffith Taylor, these pioneers first attributed the red colour to red algae. However, recent studies found that its vibrancy comes not from blood, but from iron-rich water that has been sealed under the glacier for millions of years. When this water finally reaches the surface and meets oxygen, it oxidises - the same process that makes metal rust - giving the waterfall its eerie, blood-like appearance.

What is particularly fascinating is the fact that the water stays in liquid form, despite Antarctica's extreme cold, where temperatures often drop to -19C - far below water's normal freezing point. For many decades, scientists could not understand why this was the case. However, in 2003, researchers discovered the water is packed with so much salt that it is almost twice the salinity of seawater. This lowers its freezing point, keeping it liquid even in these sub-zero conditions.

"[The] Taylor Glacier is the coldest known glacier to have persistently flowing water," lead author of the 2017 study, Erin Pettit, a professor in the College of Earth, Ocean and Atmospheric Sciences at Oregon State University, said in a statement at the time.

In 2017, researchers discovered the waterfall's hidden heart roughly 1,300 feet beneath the ice and 300 feet from the waterfall itself. The true size of the reservoir remains a mystery.

Given the extreme conditions, one might assume that nothing could live here. However, as was discovered in 2019, that is not the case. It is actually home to a unique community of bacteria that uses chemicals like sulphate and iron for energy instead of sunlight-a process called chemosynthesis.

Scientists also believe that Blood Falls was once part of a lake that existed millions of years ago. Only when the glacier shifted did the water finally escape, meaning the red stream could flow again after over a million years.

Studies into this unique environment continue. Scientists are offered an unprecedented opportunity to study deep subsurface microbial life in extreme conditions without needing to drill deep boreholes in the polar ice cap, which brings with it risks of contamination and damage to this fragile environment.

Studies are useful to help understand the strange conditions to which life can adapt and to learn more about the possibility of life elsewhere in the Solar System, in places such as Mars and Europa, Jupiter's ice-covered moon.