Devil's Kettle

In Judge C. R. Magney State Park, there's a huge rock bisecting the Brule River. The eastern flowing water cascades down a cliff and flows toward Lake Superior. The westward flowing water enters a hole and disappears into who knows where? Welcome to the Devil's Kettle! This water portal to "The Twilight Zone" is a puzzle to researchers who have attempted to map the underground water flow by dropping ping-pong balls and dye into the hole but thus far mapping the water's path has remained elusive.