The Old Faithful Area
The most famous sight in the park, Old Faithful. Located on the southern side of the park, closer to the Teton area, this whole area is named after the geyser.
The historic Inn was built in 1903, it’s one of the largest log structures in the world.
The geyser was used as a washing machine by early settlers, but it would dissolve anything but cotton clothes.
After a series of earthquakes the geyser now goes off about every 90 minutes instead of 60, also making the higher water points less frequent. Its height goes between 106 and 184 feet tall still, 130 feet being the average. Though the most famous, it's not nearly the tallest geyser in the park.
Thermophiles live in the water, thriving in 158 degree water in complete darkness just under the surface of old faithful. Almost 60% of the organisms are Thermocrinis ruber, a type of chemoautotroph. Meaning that they process CO2 that is outgassed from the geyser.
There are hundreds of types of bacteria, archaea, micro-fauna, and more creating a unique ecosystem throughout the park's waters.
Trails;
Observation Point Trails - Has many geysers, and pools along a boardwalk. Solitary Geyser goes off every 4-8 minutes and is located on the far end of this trail, about half a mile. It was a large pool/pond that was drained in the 1900s to fill a swimming pool, which accidentally turned it into a geyser. You can then walk, or drive to the;
Black Sand Basin Trailhead - if you keep following the boardwalks along the Firehole River from the geyser. To walk from the geyser, do Observation Point Trail, and Black Sand Basin, and back, is about 4 miles total. There are plenty of places to rest along the trails, there is also a parking lot for black sands that would take about a mile of boardwalks off the total.
Biscuit Basin - Currently closed after it erupted last year (2025), wouldn't bother walking all that way but you can park in the parking lot and see what’s left, there isn’t much you can see though.
Grand Prismatic Trails - are located up the road of old faithful, I would suggest waiting for later in the day to do this trail, or park down the road and walk to the trailhead as parking here is a nightmare, typically the worst between 7am-2pm and weekends. The overlook is located about .5 miles up the Fairy Falls Trail. You can continue this trail to see fairy falls, one of the tallest in the park, and there are more hot spring pools at the top of this trail. Beware there is a lot of bear activity around fairy falls, they often ‘fish’ at the base of it. Grand prismatic trails are an easy walk, maybe a half mile total on the boardwalks. I’d suggest waiting for the warmest day or the windiest you have for this as you can’t really see anything when it's cold with all the steam. The colors come from trillions of thermophiles living in the water, and steam. Grand Prismatic is the largest hot spring in the park, and 3rd largest in the world. The colors change throughout the year, summer typically shows warmer colors, while in the winter it turns cooler, more greens and blues.
Lone Star Geyser - Is one of few bike trails in the park, you can also hike to it. Beware of bees at the actual geyser there’s tons of them. It’s about 9 miles round trip. It goes off about every 3 hours, and the eruption lasts about 30 minutes. It is one of few thermal features you can actually walk up to, and the hike is beautiful. I typically see animals everytime so don’t forget bear spray here! At the far end of the trail there are connections into many miles of backpacking trails, including the Shoshone Lake trails.
Viewpoints;
Old Faithful Geyser - You can walk along the boardwalks to get closer to it, it can get very crowded here, there is a timer in the visitor center that tells you when it’s going to go off and cafeteria by it where you can eat on the deck with a view of the geyser without so much of the crowds here as well.
There are several basins you can park at and walk to, or do the whole trail listed above
Animals;
Bison, Elk, Coyote, and Black bears are often spotted in the area. The Overlook trail, and the Upper Falls trail, around dawn and dusk, are when most people report sightings.
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