Minnesota’s Brule River is the source of a unique phenomenon that’s been puzzling locals, tourists, and scientists alike. Flowing not too far from the northern shore of Lake Superior, the Brule hits a divide as it travels through a cluster of volcanic rock that juts out in Judge C. R. Magney State Park. Split in two by the rocky fork, the river begins flowing both east and west. To the east, a waterfall is born, cascading half the river down into a pool, where it eventually meets up with the lake. But that western fork is a whole different story.

Unlike its eastern twin, the waterfall at the other end of this fork seemingly pours into nothingness. Called the “Devil’s Kettle,” this natural, rocky void has no obvious explanation on or below the surface. People have tried to solve the case of the bottomless waterfall by dropping ping pong balls into the pothole and casting dyes in an attempt to mark the water, but none of those plans have given anyone any clue as to where all this water is going. That is until Minnesota’s Department of Natural Resources got involved.

By measuring the water volume both above and below the Kettle, two hydrologists, Heather Emerson and Jon Libbey, found the numbers at each location were nearly identical. This finding suggests that the Devil’s Kettle waterfall likely rejoins the river underground shortly after the fork.

"What we think is happening is the water is going in the kettle, and coming up pretty close to immediately downstream of the falls," Jeff Green, a hydrologist for the Minnesota Department of Natural Resources, told Minnesota Public Radio.

The volume of water was flowing 123 cubic feet per second above the falls and 121 cubic feet per second several hundred feet downstream from the Kettle. In the fall of 2017, Green and retired University of Minnesota professor Calvin Alexander are planning to pour a biodegradable dye into the Kettle to get a more accurate reading on where and how the water meets back up with the river downstream.

So will the end of the mystery also mean the end of the Kettle’s allure? For some people, perhaps, but as Green points out, “it will still be a fascinating spot, and a beautiful spot."