Along with Morning Glory, Grand Prismatic Spring may be the most famous hot spring at Yellowstone National Park. Grand Prismatic Spring is grand indeed. It measures about 250 feet by 300 feet and is by far the largest hot spring pool in Yellowstone. Because of its size it is very difficult (if not impossible) to get a good, complete picture of Grand Prismatic Spring when walking along the boardwalk in the Midway Geyser Basin. In order to get the really good photos you may have seen of Grand Prismatic Spring you’ll need to hike up trails that may be close or fly over the spring. The incredible amount of steam that sometimes wafts up from the spring also makes photography from the boardwalk difficult.
The center of Grand Prismatic Spring is a greenish blue color while the edges of Grand Prismatic Spring are much more colorful and make for spectacular aerial photos. As the temperature of the water cools where the spring overflows and discharges water more different types of bacteria are able to grow and crate a rainbow of colors along the edge of the spring.
Grand Prismatic Spring is located all the way at the top of the Midway Geyser Basin Boardwalk so if you should decide to hike to the end of it to see Grand Prismatic Spring you will see all the other sights in the Midway Geyser Basin on your way up to and back from Grand Prismatic Spring. Along the way you will see Excelsior Geyser, Turquoise Pool and Opal Pool.