Colorful turquoise water & red microbial mats. Grand Prismatic Spring overlook, Yellowstone NP, Wyoming, USA.
Admire colorful microbial mats contrasting with turquoise water at Grand Prismatic Spring overlook in Midway Geyser Basin, Yellowstone National Park, Wyoming, USA. Starting from Fairy Falls Trailhead (OK5), walk 2 miles round trip to the Grand Prismatic Spring overlook, up a side trail. Grand Prismatic is the largest hot spring in the United States, and the third largest in the world, next to those in New Zealand. The sterile blue water in the pool’s center is too hot to support life (87 degrees Centigrade or 188 F). Pure water selectively absorbs red wavelengths of visible light, making the center deep blue. But in cooler water along the edges, microbial mats of thermophilic (heat-loving) cyano-bacteria and algae thrive. Yellow, orange, and red pigments are produced by the bacteria as a natural sunscreen. As a result, the pool displays a spectrum of colors from the bright blue water of the center to the orange, red, and brown algal mats along the edges. Summer mats tend to be orange and red, whereas winter mats become dark green. Yellowstone was the first national park in the world (1872), and UNESCO honored it as a World Heritage site in 1978.Add to Cart Add to Lightbox Download