A red river
The Rio Tinto River is a vivid red colour that’s beautiful but toxic. Only one type of life form—a certain type of bacteria—can survive in it. Studying this extremophile is helping NASA scientists understand how life can exist in extreme conditions on other planets.
https://www.andalucia.org/en/10-unusual-facts-that-you-did-not-know-about-the-rio-tinto-river