Upper Geyser Basin
The Upper Geyser Basin has the highest concentration of geothermal features in the park. This also includes the most famous geyser in the park, Old Faithful.
Midway Geyser Basin
Midway Geyser Basin is smaller than the other basins found in Yellowstone. It does however contain two large features, the Excelsior Geyser which pours over 4,000 gallons per minute into the Firehole River. Also, the largest hot spring in Yellowstone, the 370 ft wide and 121 ft deep Grand Prismatic Spring.
Norris Geyser Basin
The Norris Geyser Basin is the hottest geyser basin in the park. It also contains the tallest active geyser in the world, Steamboat Geyser.
Mammoth Hot Springs
Mammoth Hot Springs is a large complex of hot springs on a hill of travertine. It was created over thousands of years as hot water from the spring cooled and deposited calcium carbonate.
There were times that I had no choice but to walk directly through thick gas fumes and steam billowing out of various mud pots and steam vents. The gases were so powerful and strong that I was really nauseous and very close to losing my lunch a couple different times.
I did a lot of walking/hiking and covered a lot of ground today. Despite my weak constitution at times, this really was a fun day checking out all the various unique and unusual thermal features in the park.