Boat Box Hot Spring

What to expect

Boat Box is the smallest of the Highway 75 hot springs and probably the most photographed. It is one metal tub, round and deep like an old cauldron, sitting on a gravel bar a few feet from the Salmon River. Hot water seeps out of the hillside above the highway and is piped down to the tub through a plastic hose. You sit in the tub, the river runs past your elbow, and the road is right behind you.

The name comes from an earlier wooden box that used to collect the water here. Spring floods kept wrecking it, and the metal tub replaced it. On some maps and older lists the spring appears as Elkhorn Hot Spring, and you may see both names.

The source water is about 136°F58°C. In the tub it usually settles around 110°F43°C, which is hotter than most people want to sit in. The fix is low-tech: a bucket is usually left by the tub, and you fill it from the river and pour it in until the temperature suits you. You can also pull the hose out of the tub for a while. Water quality is fine for a soak, though it is often a little cloudy because of algae, and the bottom of the tub collects grit.

Three or four people fit if they know each other well. Two is comfortable. There are no toilets, changing rooms, bins or benches. Most people change in their car.

This is a quick, scenic stop, not an afternoon destination. Plan on 20 to 40 minutes, then move on so the next car can have a turn.

Getting there

Start at the junction of Highway 21 and Highway 75 in Stanley, the spot locals call the T. Head north and then east on Highway 75, the Salmon River Scenic Byway, toward Sunbeam and Challis. You pass Lower Stanley within the first couple of miles. The road follows the Salmon River the whole way and is paved.

At about 3.5 miles from the T, between mileposts 192 and 193, watch for a small gravel pullout on the river side of the road (on your right as you head downriver). It holds only two or three cars and is easy to miss. On cold mornings the steam off the tub is often the first thing you see. If you overshoot, turn around at the next safe wide spot rather than backing up on the highway.

From the pullout, walk a few yards across sand and gravel down to the tub. It is close enough that you can carry a towel and a thermos and still have a free hand, but the bank can be icy in winter and loose in summer.

If the pullout is full, do not park on the shoulder. This stretch has fast traffic and little room. Keep going to Basin Creek or Sunbeam and come back later.

When to go

Late summer, fall and winter are the best seasons. The river is lower, the tub is easy to reach, and cool air makes 110°F43°C water feel right. Winter is a favorite: snow on the far bank, steam on the river, and fewer people on the highway. The road is plowed, but the pullout may be packed snow or ice.

Spring runoff, in late spring and early summer, pushes the Salmon up and fast. Water can reach the tub and the bank gets soft. This is the worst time to go, and the most dangerous time to step into the river.

Crowds: Summer weekends are busy because Stanley fills with campers, rafters and road-trippers. Early morning and after dark are the quiet hours. Because the tub fits so few people, even three cars in the pullout means a wait.

Rules and etiquette

The spring is on the Sawtooth National Forest, right beside a state highway, and there is no host or sign. A few things keep it working:

• No fee. You do not need a pass for the pullout.
• Wear a swimsuit. A Sawtooth National Forest order bans public nudity on all forest land and roads through September 2031, and the tub is in plain view of passing traffic.
• Keep it short when others are waiting. With one small tub, turn-taking is the whole system. Ask anyone already in how long they plan to stay.
• No soap, shampoo or glass. Glass breaks on the gravel and ends up in the river.
• Put the hose back. If you pulled it out to cool the tub, return it before you leave so the next person gets hot water.
• Pack out everything. There are no bins at the pullout.

Where to stay nearby

There is no camping at the pullout itself. Nearby options:

• Salmon River Campground, a Forest Service campground about a mile farther down Highway 75, has around 30 first-come sites, vault toilets and drinking water in season.
• Lower Stanley and Stanley, 3 to 4 miles back up the road, have motels, cabins, a few restaurants, fuel and a small grocery. Stanley books out early on summer weekends, so reserve ahead.
• Redfish Lake, a short drive south of Stanley on Highway 75, has a lodge, cabins and several large campgrounds for a longer stay in the Sawtooths.

Safety notes

• Hot water: The water coming out of the hose is far hotter than the tub. Test before you get in and do not let anyone put a hand under the hose. Do not put your head under the water.
• The river: The Salmon is cold and fast right next to the tub. In spring and early summer it can knock an adult off their feet. Fill the bucket from the edge, and keep kids and dogs out of the current.
• Traffic: You park and walk beside a fast state highway. Get in and out of your car on the river side where you can, and use lights at night.
• Ice: In winter the gravel bar, the rim of the tub and your wet feet are all slippery. Wear boots down to the tub and take them off at the edge.
• Altitude and cold: Stanley sits above 6,000 feet and winter nights often drop well below zero. Have warm, dry clothes ready in the car before you get out of the water.

Nearby stops worth adding

Highway 75 east of Stanley is a short chain of soaks. Basin Creek Hot Springs is about 5 miles farther down the road, with small rock pools by the creek mouth. Sunbeam Hot Springs is about 12 miles from Stanley and has built pools where hot water mixes with the river, plus changing rooms. Doing all three in one day is easy, and Boat Box usually works best as the first or last stop because it is so close to town.