Wyoming’s oldest state park has free hot springs and a bison herd; most people drive past it

Wyoming’s first park still honors a century-old deal

Hot Springs State Park sits on the north edge of Thermopolis, a small town in northwest Wyoming, and it has been drawing visitors since before Wyoming was even a state.

The mineral water here flows freely, the bison graze in the hills above the river, and a suspension bridge sways gently over the Bighorn. Many people pass through on their way to Yellowstone without stopping.

That’s a mistake worth correcting before you make it.

Wyoming’s first state park, open since 1897

The park started out as Big Horn Hot Springs State Reserve, and it became Wyoming’s first state park in 1897.

It sits on the north edge of Thermopolis in the northwest corner of the state, and it has grown into one of Wyoming’s most visited parks. Travelers heading to Yellowstone often pass right through this part of the state.

If you time it right, you can make Hot Springs a proper stop on that drive rather than a blur through the windshield.

A deal made in 1896 that Wyoming still honors

The story of how this place became public land starts with a negotiation.

In 1896, the Eastern Shoshone and Northern Arapaho tribes agreed to sell the land around the springs, and built into that deal was a condition: the mineral waters had to stay free to the public, forever.

Chief Washakie of the Shoshone is tied to that history. Wyoming has honored the agreement ever since.

Each August, the Gift of the Waters Pageant retells that story right here at the park.

The Big Spring flows millions of gallons a day

The park’s centerpiece is Big Spring, which the state bills as the world’s largest mineral hot spring.

Millions of gallons of mineral water flow from it every single day, and it comes up out of the ground at around 128 degrees Fahrenheit.

Someone painted “World’s Largest Mineral Hot Spring” in white letters on a hillside nearby, so you won’t miss the claim. People have been making their way here to drink and soak in these waters for well over a century.

Soak for free at the State Bath House

The state runs a free public bath house, open all year.

The water gets cooled down to 104 degrees before it reaches the pools, which is warm enough to feel genuinely good on your back and shoulders without scalding you. There are both indoor and outdoor options.

Soaks run about 20 minutes per person, and you can sometimes borrow a towel or a suit on site if you forgot yours. This is not a spa with a lobby and a price list.

It’s just a free soak, the way the 1896 deal intended.

The Rainbow Terraces change color with the minerals

Hot mineral water flows down wide, layered ledges called the Rainbow Terraces, and the colors you see, golds, reds, deep greens, come from a mix of minerals and algae living in the water.

The ledges are travertine, a soft stone the water builds up over time as it cools and deposits what it carries. Below the terraces, the water drains into the Bighorn River.

Boardwalks normally let you get close to the formations, but they’re closed through late August 2026 during a full replacement project, so check conditions before you plan your visit around them.

Cross the Swinging Bridge for the best river view

A suspension footbridge crosses the Bighorn River, and the locals call it the Swinging Bridge because of the way it moves under your feet.

It connects the park’s paths on both sides of the water, and it puts you directly above the river with the terraces in view.

It’s one of the better photo spots in the park, and the bridge itself was recently reinforced, so the sway is gentle. Cross it in the morning when the light comes in low and the steam is still rising off the pools.

The cone-shaped mound that steams day and night

One of the more unusual things in the park is a cone-shaped mineral mound that steams around the clock.

It was built in the early 1900s to vent steam from the park’s pipes, and mineral water has been flowing over it ever since, adding new layers every year.

Most people who see it assume it grew naturally from the ground. The park calls it the most photographed spot on the property.

You can stand next to it and watch the steam curl up in the air while the water trickles down the sides.

Watch the bison herd graze on the park’s hills

The park has kept bison since 1916, and this herd serves as the central herd for all of Wyoming’s state parks. About 15 animals graze in a fenced range on the hills above the river.

In the colder months, a morning feeding happens around 8:30, and you can watch from a distance while the animals move in. It’s not a zoo, and the bison are not tame.

But the setup puts you close enough to get a clear look at animals that once covered this entire region.

Six miles of paved, accessible trails wind through the park

The park has 6.2 miles of trails, and most of them are paved and accessible, with sidewalks and boardwalks connecting the main areas.

The paths take you past steaming pools, along the river, and up to spots with wide views of the park and the town below. There is also a marked Volksmarch walking route if you want a structured loop.

You won’t find a demanding climb here. These are trails you walk for the scenery, not the workout.

The park looks different in every season

Summer brings flower gardens in full bloom around the park’s main areas.

Fall turns the cottonwoods along the Bighorn River gold, and the terraces take on a different look against the cooler light.

In winter, steam rises off the pools into cold air, and the whole place feels otherworldly in a way that photos don’t quite capture. The park stays open all year.

The free bath house stays open all year. Whenever you come, the water is the same temperature it has always been.

Mule deer, bald eagles and good fishing along the river

Beyond the bison herd, the park is home to mule deer and bald eagles along the Bighorn River corridor. Anglers can fish the river right inside the park, and a boat ramp gives you water access if you bring your own gear.

Quiet picnic spots sit along the banks where the cottonwoods lean over the water. If you want a slower hour between the terraces and the bath house, the riverbank is where you go.

Visit Hot Springs State Park in Thermopolis, Wyoming

You can find Hot Springs State Park at 51 Highway 20 North in Thermopolis, Wyoming. The park charges no entry fee, and soaking at the State Bath House is free.

It’s open year-round, so there’s no bad time to go. Recent improvements include a new boat ramp and a reinforced Swinging Bridge.

Check the official website before your trip for current bath house hours and updates on the Rainbow Terraces boardwalk, which is under construction through late August 2026.

This article was created with AI assistance and human editing.

Read more from this brand:

• The science behind Grand Prismatic Spring’s colors is wilder than the colors themselves
• Where does the river go? Wyoming’s Sinks Canyon has stumped scientists for forty years
• Half the world’s geysers sit in one Wyoming basin and most visitors drive right past them