What makes Blood Falls in Antarctica appear red?

Antarctica is home to a waterfall that is known as Blood Falls because it runs with a rusty red color, though this color comes from the water's high iron content rather than the presence of actual blood. Blood Falls' color is especially dramatic in appearance because it is in stark contrast with the bright white ice fields that surround it.

Rusty red isn't just an aesthetic characterization of this water; it's also a literal description. The water that feeds Blood Falls is trapped under layers of ice and has never been exposed to oxygen. When the water exits the ice and gets exposed to air, it turns rusty due to its high iron content.