Norris Geyser Basin is a large area of thermal features. It is located at Norris Junction. This area is one of the hottest and most unstable in the park. Temperatures in many of its features tops the boiling point. It lies at the intersection of three fault lines, making it a very active seismic area. New features appear almost every year here, while others disappear or become inactive. Back Basin is a large section of Norris that is mostly forested and its features are widely spread. It is described below in a clockwise pattern, turning left past the bookstore, away from the museum. Back Basin has a huge number of features, so only selected ones are covered below.
The path leaves the parking area, passes the bookstore, and approaches the museum. Turn left towards Back Basin. Keep going straight, and soon arrive at Emerald Spring. Its color comes from water reflecting blue light combined with the yellow sulphur coating inside the pool. The pool is 27 feet deep and very hot.
The path passes through a steep section before arriving at Steamboat Geyser. When active, this is the tallest geyser in the world. The last major eruption as of January 2015 was on September 3, 2014. Water is ejected to heights of over 300 feet for up to 40 minutes. Steamboat Geyser is completely unpredictable, so it comes down to enormous luck to see such an event.
The path continues down and comes to a junction. Turn left and follow the path past Black Pit Spring to a viewing area for the Echinus Geyser. It is named for its pattern of deposits, which look like starfish (echinoderms). The eruption patterns of this geyser vary widely. It is the largest acidic geyser known, with a pH of as low as 3.
Puff ‘n Stuff Geyser
The path alternates between boardwalk and trail as it continues along the back of the loop. Several small features are passed, including the Arch Steam Vent. After a time it reaches Puff ‘n Stuff Geyser. This small geyser is in constant eruption, spraying water a few feet.
Black Hermit Cauldron
A short way from Puff ‘n Stuff Geyser is a feature called Black Hermit Cauldron.
Green Dragon Spring
The path soon arrives at Green Dragon Spring. A short side path drops down to allow a closer look. This beautiful spring’s water partly rolls out of a small cave.
Several other features are passed on the way to Pearl Geyser. This geyser’s pool is often empty. When it is not, its eruptions can reach 8 feet high. When empty, its colorful formations can be seen.
As the end of the loop nears, Minute Geyser can be seen in an area of richly colored land. It erupts nearly constantly one to three feet tall. This geyser used to be much more impressive before visitor vandals threw so much debris into it that its opening was virtually sealed.