Which national park is home to the Grand Prismatic Spring, the largest hot spring in the United States?

The national park home to Grand Prismatic Spring, the largest hot spring in the United States, is Yellowstone National Park.

Grand Prismatic Spring sits in Yellowstone’s Midway Geyser Basin, a geothermal area shaped by the park’s active volcanic system. Its vivid rings of blue, green, yellow, orange, and red are produced by a combination of the water’s depth, mineral content, and heat-loving microorganisms living around the cooler edges.

The spring is approximately 370 feet across and about 160 feet deep. Its intense blue center reflects the natural color of deep, clear water, while microbial mats around the margins change color according to temperature and the balance of pigments such as chlorophyll and carotenoids.

Geologists recorded the spring during the Hayden Geological Survey of 1871, which gave it the name “Grand Prismatic” because its colors resemble the spectrum produced when white light passes through an optical prism. A common mix-up is confusing the spring with Old Faithful, Yellowstone’s famous erupting geyser. They are separate geothermal features, although both are within Yellowstone National Park.