Devil's Kettle

A mile and a half up the Brule River the water splits around a knuckle of rhyolite. The east half falls 50 feet into a pool and carries on toward Lake Superior. The west half pours into a pothole and disappears.

For decades that was the whole attraction, and people tested it the way people do. Ping-pong balls went in. Logs went in. Dye went in. By local rumor a car went in. Nothing was reported coming out, and the stories hardened into a standing question about where the water went: a lava tube, an underground river, an outlet somewhere out in the lake.

The measurement

In late fall 2016, hydrologists Heather Emerson and Jon Libbey of the Minnesota Department of Natural Resources gauged the river above the falls and below them. Above, 123 cubic feet per second. Below, 121. Hydrologist Jeff Green called the two figures identical within instrument tolerance.

Nothing is leaving the river. The water rejoins it a short way downstream.

Calvin Alexander, a hydrogeologist at the University of Minnesota, accounted for the objects. The plunge pool recirculates hard enough to hold and break up whatever goes into it, and what it eventually releases comes out downstream in pieces too small for anyone on the bank to connect to the ping-pong ball they dropped. Geologists had already ruled out the lava tube, because neither the rhyolite nor the basalt beneath it forms them.

The experiment nobody ran

A fluorescent dye trace was planned for fall 2017, which would have put the question past argument by showing exactly where the water resurfaced. It was never carried out. Park manager Pete Mott told WTIP there was no scientific reason to do it, the gauging having already answered it.

The record therefore stands at two readings 2 cubic feet apart and one canceled experiment. The kettle still takes the water, and people still come down the stairs with something in their pocket to throw in.

A state park vehicle permit is required, $7 for the day or $35 for the year, payable at the self-registration station near the entrance.

The Devil's Kettle Trail runs about 2.25 miles round trip and includes roughly 200 stairs down into the river gorge and back up again. It took first place for best hiking trail in USA Today's 10Best readers' poll in May 2025, so summer weekends draw a crowd. The trail is open year-round, though the stairs are not maintained in winter and the riverside section north of the kettle still carries flood damage.

Rock at the overlook stays wet from spray, and there is no railing at the kettle itself. Spring high water covers the lower ledges.

The campground and ranger station run from mid-May to late October. The nearest supplies are in Grand Marais.