With the presence of half of the earth’s geothermal features or “remarkable curiosities” as they were sometimes called back around the time of the creation of the park, Yellowstone stands alone as the premier place to view geysers, hot springs, mud pots, and fumaroles. At the time of the parks designation in1872, herds of bison roamed large sections of the United States while grizzly bears had an even greater distribution. How things change. So it was not Yellowstone’s animals, but its more than 300 geysers and 10,000 plus thermal features which persuaded America that Yellowstone should be “reserved and withdrawn from settlement, occupancy, or sale under the laws of the United States, and dedicated and set apart as a public park or pleasuring ground for the benefit and enjoyment of the people.”
Geothermal, as the name implies, means heat. Geothermal comes from the Greek words "geo" (earth) and "therme" (heat). Most of the earth’s heat is produced by the radioactive decay of potassium-40, uranium-238, uranium-235, and thorium-232. This heat helps form the magma that, every 600,000 years or so erupts from the Yellowstone Hot Spot. Yellowstone’s geothermals are the park's most recent evidence of this radioactive decay. Canyon Village Educational Visitor Center, Norris Geyser Basin Museum, Park Service brochures located at popular thermal trailheads and Windows into the Earth: The Geologic Story of Yellowstone and Grand Teton National Park Robert B. Smith and Lee J. Siegel, are all good sources for more information about these "remarkable curiosities.
There are many different types of geothermal activity that you can see in Yellowstone. There are of course geysers, which periodically erupt boiling hot water and steam to heights over 100 ft in the air. Hot Pools that sometimes look bottom less and are filled with neon colors seemingly so unnatural but natural they are. You may see fumaroles, geothermal features where steam is constantly being released from; sometimes with such great force that one would expect the fumarole to explode at any moment. Mud pots are areas of clay that have been infiltrated by hot gas and water which percolate up through the clay, turning the clay in to a malleable plastic looking material. And hot springs flowing out of the ground large enough to form fair sized creeks.
Mammoth Hot Springs is, as the name implies, mammoth. The area has many different springs covering at least ½ square mile of hilly terrain. Boardwalks have been built so that you can climb the hillside created by the deposition of calcium carbonate precipitated from the waters of the hot springs. It's been said that the best way to get a hot spring to stop flowing is to build a boardwalk to it. And true to this saying, there are a lot of boardwalks covering Mammoth Hot Springs that lead to dried-up springs. As of the writing of this book (2011), I find that the Palette Spring/Liberty Cap area at the base of the main hillside about 300 yards southwest of the general store and gas station is the most active with hot water. Just imagine that the earth is forming right before your eyes when standing in front of Palette springs because it actually is! Also imagine that you are looking at a living entity because much of what you are looking at is alive with bacteria and algae called thermopiles. I check out this area and then hop in the car and go to Upper Terrace Drive above Mammoth. This little drive is always worth the short amount of time it takes. Also, while on Upper Terrace Drive, I would check out Canary Springs that flows down the hillside from near the parking lot that overlooks Mammoth
Boiling River Hot Springs is a "must do. The springs are the only place, near the road in Yellowstone, where you are allowed to go “hot potting” or swim in. The waters are the perfect place to rest your sore muscles after a long hike and/or just marvel at the wonderment of Yellowstone. Boiling river is closed, due to high water between the approx. dates of June 1 and July 4. See the "Best of Yellowstone" section for more detail.
Fountain Paint Pots is, well, muddy but worth the half mile round trip along the boardwalks. Get ready to see one of the strangest things you have ever seen – a bed of clay that has been infiltrated by a small hot spring. The clay has been turned into a strange malleable plastic-like material. Hot gases periodically escape through the clay forming little mud volcanoes. As you continue along the boardwalk, there are interesting fumaroles, hot pools and geysers to check out. Fountain Paint Pots is located between Midway and Lower Geyser Basin.
Grand Prismatic Spring This hot pool is the largest and most colorful in the park. Only “seeing is believing” as the old saying goes. The blue, green, orange neon colors must be where Grand Prismatic got its name. A short hike from the road will take you this magical spot that will let you view into one of the universe most beautiful natural wonders. See the "Best of Yellowstone" section.
Old Faithful Geyser is the most well-known icon of Yellowstone Park. It is also the most visited place. But don’t let that get in your way, just get your “best” attitude on and go brave the crowds. There is an unbelievably large log inn from which to view Old Faithful erupting almost 100 ft into the air. Be sure to walk around the geyser basin that is near the inn and Old Faithful. This is my favorite geyser basin in the park and has many different types of geothermal features. See the "Best of Yellowstone" section.
West Thumb Geyser Basin is the good place to get a close look into deep, colorful hot spring pools. It is also the home of Fishing Cone which is a small thermal geyser located in Yellowstone Lake just a few feet from the boardwalk. There is a well-known historic photo of a fisherman lowering a cutthroat trout into Fishing Cone while still hooked to his fishing line. Please don’t try this yourself. Walking around the basin only takes about 45 minutes. As the name implies, West Thumb Geyser Basin is located on the shore of the West Thumb of Yellowstone Lake. This area of the lake was formed by a large eruption that occurred approximately 150,000 years ago.
Mud Volcano geothermal area is different from the other areas mentioned so far. The features are somewhat larger and generally muddier in appearance than the others, with the exception of Fountain Paint Pot. The Dragon's Mouth Spring (one of the springs located in this group) is unique in that waves of water surge from a cave located on the hillside. You can easily imagine the early explorers hearing the noise of the escaping gases pulsing from Dragon's Mouth Spring from ¼ mile away and wondering what could possibly be making such a sound. The spring has quieted since the 1870’s, but is still quite impressive. Mud Volcano is located at the south end of Hayden Valley.