In the world’s most extreme conditions, expecting a waterfall in a desert would be considered foolish. However, in Antarctica’s McMurdo Dry Valleys, a waterfall emerges from the Taylor Glacier, towering as high as five stories, and its water is a striking blood-red color.

Five million years ago, rising sea levels caused flooding in East Antarctica, forming a salty lake. Millions of years later, glaciers formed over this lake, cutting it off from the rest of the continent. This means that the water of the bloody waterfall is essentially a “water time capsule” that has been preserved underground for millions of years, 400 meters below the surface.

As the glaciers began to freeze above the lake, the water below became increasingly saline. Today, the subglacial lake beneath the bloody waterfall is three times saltier, preventing it from freezing.

Not only is this water isolated from the rest of the continents, but the water that flows out as a waterfall is also completely disconnected from the external environment; it has never been exposed to sunlight and is devoid of oxygen.

This waterfall is also very high in iron. When the iron-rich water emerges and comes into contact with the air, it oxidizes, causing it to rust and appear blood-red when it falls onto the ice.