This is an aerial view of Grand Prismatic hot spring in Yellowstone National Park, U.S.A. Several types of microbes thrive in the extreme environments of hot springs like this one. Some organisms even prosper in highly acidic hot springs! The rainbow hues of some hot springs are produced by various colors of microbes that live in different temperature niches within each spring.
Image courtesy of the U.S. Natl. Park Service, photograph by Al Mebane.