Hot Springs State Park, Thermopolis

What to expect

Hot Springs State Park sits at the northern edge of Thermopolis, a town of about 3,000 people in Hot Springs County in the Big Horn Basin of central Wyoming. The park is compact enough to cover in a few hours, but specific enough that it tends to hold people longer than expected. The Big Spring is the centerpiece: a geothermal source that delivers water at around 135 degrees Fahrenheit continuously, producing a flow rate that puts it among the largest mineral hot springs on earth by volume. The water cools as it travels down through the terrace system toward the soaking pools, reaching roughly 104 degrees Fahrenheit by the time you step into the State Bath House.

Travertine deposits have built bright orange-and-white terraces along the hillside and the Bighorn River edge over thousands of years, similar in process to the formations at Yellowstone but without the long drive or the entrance fee. A small bison herd roams the north section of the park and is visible from the main road through the grounds. The park sits within Wind River Country, the broad central Wyoming region that also encompasses Lander, Pinedale, and the backcountry areas to the south. This is one of Wyoming's most accessible and genuinely free natural attractions, and it belongs in any honest list of the best state parks in Wyoming: no timed entry, no vehicle fee, and open every day of the year.

What to do there

The Hot Springs State Park Bath House on Tepee Street is the main draw. It is genuinely free, funded by the state under the terms of the 1896 land deed through which the Shoshone and Arapaho tribes transferred the springs to Wyoming, with a permanent stipulation that the waters remain open to the public at no charge. Sessions run 20 minutes: you sign in at the front desk, stow your things in a locker (the lockers have no locks, so leave valuables in your car), pass through the gender-separated showers, and choose between an indoor pool or an outdoor pool, both maintained at approximately 104 degrees Fahrenheit. You sign out when you leave. If you want a second session, you can sign back in and wait for space. The outdoor pool is particularly worthwhile in fall and winter when steam rises off the surface against cooler air.

Beyond the Bath House, the walking path along the travertine terraces is a flat 20-minute loop that delivers the best views of the mineral-stained formations and the Bighorn River below. A suspension bridge crosses the river within the park and is worth the short walk just for the upstream and downstream views. For something more physical, the Spirit Trail switchbacks up the hill behind the falls to an overlook above the park; plan on 40 to 55 minutes round trip. The bison in the north section are accustomed to vehicles but still require the standard 25-yard buffer.

The full hot springs experience in Wyoming pairs naturally here with a visit to the Wyoming Dinosaur Center on Carter Ranch Road, about half a mile from the park entrance. The museum holds full-mount dinosaur skeletons, hands-on fossil preparation labs, and summer dig programs where visitors join active excavations for a half day or a full day (estimate: $175-$220 per adult for dig access; museum-only admission runs approximately $12-$18 for adults, less for children). For dinner after a soak, One Eyed Buffalo Brewing Company on Broadway Street in downtown Thermopolis brews on-site craft beers and serves a menu that leans on bison burgers and pub food.

Getting there and access

Thermopolis sits at the intersection of US-20 and US-789 in the Big Horn Basin, about 130 miles west of Casper on US-20, which is roughly a 2-hour drive from Casper's airport (CPR). Cody (COD) is about 85 miles north on WY-120, around 1 hour and 40 minutes in clear weather. Jackson Hole Airport (JAC) is roughly 185 miles to the southwest via US-26 and US-789, about 3 hours under normal conditions. Visitors flying into Billings (BIL) in Montana can reach Thermopolis in approximately 3 hours by driving south on US-310 to Greybull and then continuing south on US-20.

A rental car is the only practical way to reach Thermopolis. There is no regional bus service or transit connecting the town to larger Wyoming cities. Once in the park, parking is free throughout. The park entrance is off US-20 on the north end of Thermopolis; the Bath House is a short drive inside the grounds on Tepee Street. The Wyoming Dinosaur Center is on Carter Ranch Road off WY-789 on the south side of town, about 3 miles from the Bath House by road.

If you are routing a longer central Wyoming trip, Thermopolis connects southward about 75 miles to Lander and the trailheads for the Wind River Range, or northward about 85 miles to Cody and the East Entrance to Yellowstone.

Best time to go

The park is open year-round, and the springs flow at the same rate and temperature in every season. Summer (June through August) brings the most visitors along with the hottest valley temperatures: Thermopolis regularly hits 90 to 95 degrees Fahrenheit in July and August, which makes sliding into a 104-degree pool feel less appealing than you might expect. That said, the Spirit Trail hike works well in the early morning before the heat peaks, and the Wyoming Dinosaur Center provides a useful air-conditioned option for the middle of the day.

Fall (September and October) is the most comfortable stretch. Air temperatures in the 55 to 70 degree range make the outdoor pool genuinely relaxing, the steam over the water becomes more visible as the air cools, and golden cottonwoods line the Bighorn River corridor through the park. Visitor numbers drop sharply after Labor Day.

Winter (December through February) is worth considering, especially if you are already traveling through the Big Horn Basin. A 104-degree outdoor soak on a clear 20-degree Wyoming afternoon, with snow on the surrounding hills and steam rising straight up in the still air, is a specific kind of experience you can only get in a place like this. The Bath House stays open through most of the winter, though hours often shorten to roughly 10am-5pm; confirm current hours before making the drive. Spring (April and May) brings lower visitation and runoff season: the terrace formations often show stronger mineral coloring after recent rain.

Good to know

The State Bath House soaking is free with no strings. The 20-minute per-session limit is enforced through the sign-in and sign-out system at the front desk; staff track entries. You can re-enter for a second session by signing out and waiting for capacity. The lockers inside have no padlocks, so leave phones, cameras, and wallets in your car or vehicle. Bring your own towel and consider flip-flops for the wet floors. The springs carry a mild sulfur smell that is more noticeable indoors than out.

Thermopolis has a small downtown along Broadway Street with several sit-down restaurants and a handful of independently owned motels. Nightly rates at local properties typically run in the $90-$150 range (estimate), which makes Thermopolis one of the more affordable overnight stops in Wyoming compared to Jackson or Cody. For most visitors coming from those cities, this is a half-day or full-day detour rather than a multi-night base.

Dogs are welcome throughout the park grounds on a leash but are not permitted inside the Bath House facility. The park has no entrance fee, no vehicle fee, and no reservation system. The bison herd in the north section is state-managed; follow the same distance rules you would in a national park, 25 yards minimum, and do not approach on foot. Wheelchair access covers the main terrace path and Bath House entry; the Spirit Trail is not accessible.