Grand Prismatic Spring

Introduction to Grand Prismatic Spring

The Midway Geyser Basin's Grand Prismatic Spring is the largest hot spring in Yellowstone and one of the largest hot springs in the world. Measuring approximately 370 feet in size and around 121 feet deep, its rainbow waters are what truly make it fascinating. While the center of the pool's cerulean hue is quite characteristic, the deep reds and greens, bright yellows, and fiery oranges encircling the edges are not as common. These vivid colors are caused by thermophilic bacteria that thrive on the rich minerals produced by the water around the hot spring. Although the center appears blue, this is due to the blue wavelengths of light being scattered, giving the illusion of a blue color.

Photography and Viewing Tips

Optimal Viewing Point

Due to the steam, some visitors might want to take a photo of the Grand Prismatic Spring from above to capture its brilliant colors. Located away from the main boardwalk, the Grand Prismatic Overlook Trail is a 1.5-mile out-and-back path that offers a great view of the spring. This area opens in late May due to bear activity and offers a small parking lot, located about a mile south of Midway Geyser Basin.

Visitor Experiences

Recent visitors have praised the rainbow array of the spring, one of the park's most photographed sights. Several commented on the crowded boardwalks during their summertime visits. Other visitors mentioned there were fewer visitors and more parking available earlier in the day (before 10 a.m.). A frequent visitor to Yellowstone noted that fog can linger in the morning, so checking the weather is advised. Several people mentioned it was difficult to get a good photo with the steam and intense sunlight and suggested heading to the overlook for better photography.

Location and Accessibility

Grand Prismatic Spring is situated about 7 miles north of Old Faithful and approximately 44 miles from the South Entrance. There's a parking lot available at the spring, though it is often busy throughout the day. The closest food and beverage concessions along with restrooms are located at Old Faithful. Access to the Grand Prismatic Spring is included in Yellowstone's seven-day pass ($35), and there are no set hours of operation. Park rangers advise exercising caution around the hot springs, staying on the boardwalks, and keeping children away from the near-boiling water.

Additional Information

For more information, visit the National Park Service's Grand Prismatic Spring page.