Rainbow on Land by Robby Edwards
Yellowstone National Park, July 2006
The vivid colors of Grand Prismatic Spring, third largest hot spring in the world, are the result of bacteria in the water. The various colors change according to the season: in the summer oranges and reds are present, and during the winter a dark green color usually abounds. The center of the pool has a deep blue color as a result of the high temperature and depth of the water.