Milford Sweat Hot Spring

What to expect

Milford Sweat Hot Spring is a small warm pool in the high desert east of Carey, where the Craters of the Moon lava fields run up against sagebrush hills. Warm mineral water seeps out of the hillside and also bubbles up through the gravel bottom of a pool rimmed in black basalt. The water is pale blue and clear when the pool has been left alone.

The pool is modest. Visitors have described it as roughly 8 by 15 feet, or about 12 feet across, and up to about 4 feet deep depending on how much sediment has built up. A 2002 visit recorded 95-98°F35-37°C, and a visitor in early September found about 100°F38°C. That is closer to a warm bath than a hot soak, and in cool weather it can feel too cool to sit in for long. A few reports quote higher temperatures, so it may vary with the season.

The spring goes by several names. Local soakers call it Carey Hot Springs, Milford Hot Springs or Desert Rose Hot Springs, and map apps usually label it Wild Rose. Milford Sweat is the name used by some hot spring lists. They all mean the same pool.

There are no facilities of any kind. You are steps from a busy US highway, though the road is not visible from the water.

Land and access

This is the most important thing to know before you go. The spring sits on private land just outside the boundary of Craters of the Moon National Monument and Preserve. The surrounding land is a patchwork of public and private ground, and the property lines are not obvious on the ground.

As of a 2025 news report, the landowners allowed people to soak and had stayed hands off. That is a courtesy, not a right. There is no official access agreement, and access could be restricted at any time. If you find a sign saying the pool is closed, respect it.

How visitors behave is what keeps places like this open. In April 2025 a longtime soaker found the spring badly littered and put up a handmade sign asking people to stop. She and two other Blaine County locals then pulled out more than 100 pounds of trash, including broken beer bottles, a dirty diaper, underwear, full food cans and aquarium fish someone had dumped in a warm pool. A 2002 report had rated the trash level here as extreme. Other Idaho springs have closed after this kind of abuse, and soakers worry this one could be next.

Getting there

From Carey, drive about 9.5 miles east on US-20/26/93, the shared highway that runs toward Craters of the Moon and Arco. Watch for a gravel turnout on the left (north) side of the road. Park there and follow the path toward the hill for about 100 yards to the pool.

Any car can reach the pullout. Slow down well ahead of time, signal early, and pull fully off the pavement, since traffic on this stretch moves fast.

Arco is about 34 miles further east and is the nearest town in that direction with fuel and food. Carey is closer for basic supplies.

When to go

The spring is reachable all year from a paved highway. Because the water is only warm, it is most pleasant on mild days in spring and fall. In summer the desert can be hot and the pool feels tepid. In winter, sitting in roughly 95-100°F35-38°C water in freezing air is a short soak at best.

Use has been heavy in past reports. Weekday mornings give you the best chance of a clean, quiet pool.

Rules and etiquette

There is no posted rule set that we could confirm, so act as a guest on someone’s land:

• Pack out everything, and take a bag for trash other people left. This matters more here than at almost any spring in Idaho.
• No glass. Broken bottles were one of the main problems in the 2025 cleanup.
• No soap, shampoo or dumping anything in the pool, including fish.
• Wear a swimsuit. The pool is a short walk from a US highway and you cannot be sure who will walk up.
• No camping or fires at the spring.
• Respect closures or signs from the landowners.

Where to stay nearby

• Lava Flow Campground at Craters of the Moon sits in a young lava flow near the park visitor center. It has grills and picnic tables, seasonal water and flush toilets, and is paid by credit card at a fee machine. It usually closes to vehicles when the loop road shuts in November and reopens in April or May.
• Silver Creek and Fish Creek Reservoir, are free BLM campgrounds west of the park.
• Carey has basic services. Arco, about 34 miles east, has motels and restaurants. Hailey and Ketchum, to the northwest, have the widest choice of lodging in the area.

Safety notes

• Water quality: This is a small, heavily used pool with no flushing system beyond the spring flow. Keep your head out of the water and skip it if you have open cuts.
• Broken glass: Wear sandals or water shoes in and around the pool.
• Highway: Watch for traffic when you pull in and out, and keep kids and dogs away from the road.
• Sharp rock: Basalt around the pool is rough and can cut feet and hands.
• Desert weather: Summer heat and winter wind are both serious out here. Carry water.

Nearby stops worth adding

Craters of the Moon National Monument and Preserve is the obvious pairing. The visitor center and loop road lead to cinder cones, lava tubes and short trails across young lava flows. Check the park website for cave permits and loop road dates before you go.