Hot Springs State Park in Thermopolis, Wyoming, is one of the most extraordinary geothermal destinations in the country — a place where the state has protected access to mineral-rich waters for everyone, by law, free of charge. Tucked into the Big Horn Basin along the Wind/Bighorn River, this park draws visitors who come for the soaking and leave having experienced something genuinely rare: a hot spring destination that balances commercial luxury, community bathhouses, dramatic mineral formations, and roaming bison all within a single compact park. Whether you’ve been chasing hot springs for years or this is your first time, Hot Springs State Park belongs near the top of your list.
Why Hot Springs State Park Is Unlike Any Other
Most hot spring destinations in the American West require a hike, a high-clearance vehicle, or at least an adventurous spirit. Hot Springs State Park is different. It’s a developed, fully accessible park sitting at the edge of a small Wyoming town — but don’t mistake accessibility for mediocrity. The springs here are among the most geologically significant in North America.
At the center of everything is Big Spring, considered by geologists to be the largest single-source mineral hot spring in the world. Millions of gallons of mineral-laden water pour from the earth every day, flowing over colorful terraces before feeding the park’s soaking facilities downstream. You can stand at the edge of the primary outflow and feel the heat radiating from the earth in a way that makes the geology viscerally real — this isn’t a tamed pool fed by pipes. This is the earth doing something profound, right in front of you.
The park’s special status comes from a treaty condition dating back to 1896, when the Eastern Shoshone and Northern Arapaho tribes ceded this land to the state on the condition that the healing waters remain free to the public in perpetuity. Wyoming has honored that commitment. The State Bath House, operated within the park, offers free soaking to anyone who walks through the door. In a landscape where hot spring access increasingly comes with a price tag, this is both historically significant and practically wonderful.
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Big Spring: The Source of Everything
Big Spring is the geological heart of Hot Springs State Park, and spending time near it before you soak is worth every minute. The outflow is striking — a massive, steaming pour of water that cascades over mineral terraces in ribbons of orange, yellow, rust, and pale green, the colors painted by thermophilic bacteria and mineral deposits laid down over thousands of years.
The water at the source is scalding — far too hot for bathing — but as it flows away from the primary vent and cools across the terraces, it reaches the temperature ranges used by the park’s soaking facilities. This natural cooling process is visible as you walk the path along the terraces, watching steam rise from water that transitions from barely touchable to perfectly soakable over the course of a few hundred yards.
The spring’s daily output is staggering by any measure. Watching that volume of water emerge from a single point in the earth gives you a sense of what lies beneath the Big Horn Basin — a vast geothermal system that has been active for millions of years. Early visitors to this area, including Indigenous peoples who used these waters for healing long before European contact, clearly understood that something exceptional was happening here.
The Rainbow Terraces: Wyoming’s Most Colorful Geology
The Rainbow Terraces are the park’s most photographed feature for good reason. As mineral-rich water flows from Big Spring across the hillside, it deposits travertine and other minerals that build up into tiered formations over time — similar in concept to Yellowstone’s Mammoth Hot Springs, though on a smaller and more intimate scale.
The coloration is the thing that stops people in their tracks. Vivid bands of orange and rust from iron-oxidizing bacteria, pale yellows from sulfur-based microbes, greens and browns from algae adapted to extreme temperatures — all of it layered across the terraces like a geological painting that changes subtly with the seasons, the light, and the temperature of the water flowing over it.
Morning is the best time to photograph the terraces. Low-angle light catches the steam rising off the hot water and turns the mineral colors luminous. In winter, when cold air meets hot water, the steam effect becomes even more dramatic, and the contrast between snow on the surrounding hills and the vivid warm tones of the terraces is genuinely surreal.
A boardwalk path lets you walk alongside the terraces without disturbing them. Take your time here. This formation took centuries to build, and the biological communities living on it are found in very few places on Earth.
Soaking Options in the Park
Hot Springs State Park offers multiple soaking experiences, ranging from completely free to commercial resort-level. This variety is part of what makes it such an appealing destination for all types of travelers.
The State Bath House (Free)
The State Bath House is the fulfillment of the original treaty promise — free, public mineral soaking for anyone who visits. It’s a clean, well-maintained facility with indoor soaking pools fed by the park’s mineral water. There’s nothing stripped-down or spartan about it; the state has maintained this facility with genuine care. You can walk in, change, soak in naturally mineral-rich water for as long as you like, and walk out without spending a cent.
This makes Hot Springs State Park one of the few developed hot spring destinations in the entire country where a world-class soaking experience is genuinely accessible to everyone regardless of budget. That’s not a small thing.
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Star Plunge
Star Plunge is the park’s commercial water attraction, operated by a private concessionaire within the park boundaries. It offers a more resort-style experience with additional amenities and multiple soaking pools using the same mineral water that feeds the State Bath House — the same source, the same minerals, different packaging.
If you’re traveling with kids or want a bit more variety in your soaking experience, Star Plunge delivers that. It’s a modest fee by resort standards, and the water quality is identical to what you’ll find in the free facilities.
Tepee Pools
Tepee Pools is the park’s other commercial soaking facility, also fed by Big Spring water. It offers a slightly different atmosphere and layout than Star Plunge, and local regulars often have strong opinions about which they prefer. First-time visitors should know that either option will put you in genuine mineral water from one of the world’s most remarkable springs.
The fact that you have three distinct soaking options — one free, two commercial — within a single park, all using the same extraordinary water, is genuinely unusual in the American hot spring landscape.
The Bison Herd: A Bonus You Didn’t Expect
Walking between soaking facilities, you may find yourself pausing to watch a small herd of American bison grazing in a large enclosure within the park. This is not a gimmick or a tourist afterthought — the herd is a genuine wildlife preservation effort that has been part of Hot Springs State Park for over a century.
The bison are clearly used to human presence but are not domesticated. Watch them from the designated viewing areas and don’t approach the fencing. Seeing a bison in the morning light, steam rising from the terraces behind them, with the Big Horn River visible in the distance — it’s a quintessentially Wyoming moment that you don’t have to hike ten miles to experience.
For wildlife photographers, the combination of geothermal features and large mammals in proximity is rare. Plan time to walk the perimeter of the bison area, especially during golden hour when the light is best.
Planning Your Visit
Hot Springs State Park is located in Thermopolis, a small town in Hot Spring County (yes, the county is named for these springs) in north-central Wyoming. The Big Horn Basin is one of Wyoming’s more remote regions, which means getting here requires commitment — but that’s also part of the appeal.
Getting Here
Thermopolis sits roughly in the center of Wyoming, making it accessible from multiple directions. Cody and the east entrance to Yellowstone are within a couple of hours to the northwest, which makes Hot Springs State Park an excellent add-on to a Yellowstone trip. Casper is the nearest larger city to the southeast. For a deeper look at Wyoming’s hot spring landscape, explore our complete Wyoming hot springs guide — the state has over 160 springs in the Soakr database, and the Big Horn Basin region alone has more than most visitors realize.
Best Time to Visit
Hot Springs State Park is a four-season destination, which is relatively rare in the world of natural hot springs. The soaking facilities operate year-round, which means that winter is actually one of the best times to visit. Cold air combined with hot water creates dramatic steam effects on the Rainbow Terraces, and the crowds that characterize summer visits largely disappear.
Summer is the busiest season, particularly July and August when Wyoming tourism peaks. If you visit in summer, plan to arrive early in the morning to get parking and avoid the midday rush at the free facilities.
Spring and fall offer a middle ground — reasonable weather, smaller crowds, and the terraces at their most photogenic as seasonal plants add color to the surrounding landscape.
What to Bring
Pack what you’d bring to any hot spring visit: a towel, a bag for wet clothes, sandals or flip-flops for walking between pools and changing areas, and a water bottle (soaking in hot mineral water dehydrates you faster than you expect). If you’re planning to photograph the Rainbow Terraces, a polarizing filter helps cut the glare on the mineral surfaces in midday light.
For a full packing guide applicable to hot spring visits anywhere in the country, our hot springs camping guide covers gear and preparation for overnight and multi-day soaking trips.
Visiting Safely
Hot Springs State Park’s infrastructure makes it one of the safer hot spring destinations in the country — properly managed facilities, clearly marked pathways, and professional oversight reduce the risks you’d encounter at a primitive backcountry spring. That said, basic safety principles apply everywhere.
Don’t enter water directly from the source or from any channel where the temperature hasn’t been verified. The outflow near Big Spring is hot enough to cause serious burns, and this is true even if the water looks calm and inviting. Stick to the designated soaking areas.
Drink plenty of water before and after soaking. Mineral spring water is not drinking water — stay hydrated with plain water separate from your soak. If you have cardiovascular conditions or are pregnant, consult a physician before soaking in any hot spring.
Keep children in designated soaking areas and supervise them closely. The commercial facilities have staff who can help with safety questions if you’re unsure about anything.
For a deeper dive into hot spring safety, our hot springs safety guide covers everything you need to know before visiting any spring, whether developed or primitive.
Beyond the Soak: Thermopolis and the Big Horn Basin
Thermopolis is a small town, but it punches above its weight as a destination. The Wyoming Dinosaur Center, located just outside of town, houses an impressive collection of fossils excavated from the surrounding basin — including a full-mounted Tyrannosaurus rex and several other significant specimens. If you’re traveling with children or simply have any interest in paleontology, this is worth several hours of your time.
The Wind/Bighorn River that flows through the park offers fishing access in season, and the canyon country surrounding Thermopolis rewards exploration. Legend Rock Petroglyph Site, a short drive from town, contains one of the largest concentrations of prehistoric rock art in Wyoming — over 200 petroglyphs covering a sandstone cliff face, some estimated to be over 10,000 years old.
For those building a longer Wyoming hot springs itinerary, pairing Hot Springs State Park with the springs in and around Yellowstone creates a genuinely extraordinary trip. Hot springs near Yellowstone are some of the most spectacular in the world, and the park’s geothermal landscape provides important context for understanding what you’re experiencing at Big Spring.
What to Expect on Your First Visit
First-time visitors often underestimate how much there is to do at Hot Springs State Park beyond simply soaking. Budget a full day if you can — a morning walk along the Rainbow Terraces, time with the bison herd, soaking at the State Bath House, and a late afternoon return to the terraces for golden-hour light will fill every hour comfortably.
The park is well-signed and easy to navigate on foot. Parking is available near the main facilities, and the loop around the terraces and bison area is walkable for most visitors regardless of fitness level. This is one of the more accessible hot spring destinations in the country, genuinely welcoming to visitors with limited mobility, families with young children, and anyone who wants the experience of world-class mineral soaking without a strenuous approach.
The combination of free public access, extraordinary geology, wildlife, and a welcoming small town makes Hot Springs State Park a destination that earns repeat visits. Most people who go once find themselves planning to go back — and they do.
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