This is an aerial view of a hot spring in Yellowstone National Park, U.S.A. This large pool is called Grand Prismatic hot spring. Hot springs are an extreme environment, but some kinds of microbes can live in them. The water in some hot springs is a strong acid, but some microbes manage to live in those, too. Different kinds of microbes have different colors. The colored microbes make this spring look like a rainbow!
Image courtesy of the U.S. Natl. Park Service, photograph by Al Mebane.