The Grand Prismatic Spring is the largest hot spring in the United States, located in Yellowstone National Park. It measures about 370 feet in diameter and is known for its vibrant colors, which are caused by heat-loving microorganisms called thermophiles. The spring's temperature can reach up to 188°F (87°C), making it one of the hottest springs in the world. The striking colors of the Grand Prismatic Spring range from deep blue in the center to bright orange and yellow at the edges. These colors are a result of the different types of bacteria that thrive in varying temperatures. The spring is a popular attraction for visitors, offering stunning views and unique natural beauty.