The Grand Prismatic Spring is an excellent tourist attraction in Yellowstone National Park. It is actually the largest hot spring in the USA, therefore the 3rd largest on the planet, It reaches up to a maximum deepness of around 50 meters and has several wonderful vibrant colors. The variety of colors are created as a result of bacterial activity around the sides of the (in which it is less hot). Prismatic Spring was pointed out by geologists doing work in the Hayden Geological Survey of 1871, and also named by them for its attractive coloration. Its colors include blue, green, yellow, orange, gold, red and brown, and the rainbow dispersion of white light by an optical prism.