Midway Geyser Basin - Grand Prismatic Spring
Updated: Nov 10, 2021
Midway Geyser Basin, although a part of Lower Geyser Basin, gets its name because of its isolated location, midway between Lower and Upper Geyser Basins. Of all groups of geysers and hot springs in Midway Basin, Excelsior Group is the most popular destination. It features two of the worlds largest hot springs, Grand Prismatic Spring and Excelsior Geyser.
Grand Prismatic Springs
The Excelsior Group of Midway Geyser Basin is accessible by a short loop boardwalk trail. The trail crosses over Firehole River and runs along large and colorful geysers and hot springs. The trail sits on very unstable ground and is surrounded by small step-like terraces and bright orange microbial mats.
Beginning of boardwalk / Trail over mineral terraces
Turquoise Pool: Turquoise Pool is a quiet pool with blue colored water and orange rim. It has had no known eruptions or overflows, instead the water drains through seepage.
Opal Pool: It is a small pool with very irregular and infrequent eruptions. When it does erupt, it typically reaches a height of about 30 feet. It erupts as one sudden burst followed by smaller splashes that last a total of one minute.
Grand Prismatic Spring: Grand Prismatic Spring, approximately 200 feet wide and 160 feet deep, is the largest hot spring in USA and one of the largest in the world. It is one of the most beautiful rainbow colored hot springs in Yellowstone National Park with deep blue color water in the center and orange brown bacteria mats around. The spring sits on a horizontally level mound where water flows evenly on all sides. It pours almost 500 gallons of water each minute into the Firehole River. Mineral deposits from this water gradually built the small step terraces around this spring.
Terraces around the spring
Bacteria Mats and Terraces / Grand Prismatic Spring
Excelsior Geyser: Until 1880s, Excelsior Geyser was one of the largest in the world. It had numerous violent eruptions up to 300 feet high. Now it remains a dormant hot spring, boiling and churning water within its crater, puffing up dense steam and producing huge run-offs, almost 6 million gallons of water per day into the Firehole River. Thick steam often disrupts the view of the crater.
Excelsior Geyser Crater / Excelsior Geyser run-off
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