Grand Prismatic Spring, United States: The Grand Prismatic Spring In Yellowstone National Park Is The

Grand Prismatic Spring, United States: The Grand Prismatic Spring in Yellowstone National Park is the largest hot spring in the United States, and the third largest in the world, after Frying Pan Lake in New Zealand and Boiling Lake in Dominica. It is located in the Midway Geyser Basin... The bright, vivid colors in the spring are the result of microbial mats of thermophilic bacteria around the edges of the mineral-rich water. Wikipedia