The beauty of nature is that some parts of it remain totally mysterious to us. What causes a rainbow? Why is grass green? Where in the ever-loving heck does the water from Devil's Kettle Falls drain out to??
Located by Lake Superior's northern shore, where the Brule River forks in Judge C.R. Magney State Park in Grand Marais, lies a geological anomaly. There's a double waterfall. That's not the weird part. One side of the falls clearly continues on into a river. Whereas the other side of the waterfall empties into a hole that goes deep into the earth. No one's been able to figure out where the water drains out to.
The river drops 800 feet over the course of 8 miles, resulting in several waterfalls. But, it's one of these waterfalls that has left geologists and scientists baffled for years. At the Devil's Kettle falls, half of the Brule River goes down some rhyolite rock, but then the falls split and no one knows where the other half of the falls empty out to. Many believe that the pothole must empty out somewhere beneath Lake Superior. So, researchers have tossed so many items into the hole over the years including ping pong balls and dye, but no one has ever found any sign of them anywhere else.
The only thing that scientists seem to agree on is the possibility of a massive subterranean river. But, that would be an extremely rare phenomenon. A more plausible answer is that the falls empty into a millions-year old lava tube, and is deposited into the very bottom of Lake Superior. However, no lava tubes have ever been found in the many "exposed basalt beds" in the surrounding area.
"So where does the water go? So far, nobody knows — but not for lack of trying. Scientists and hikers will keep tossing things into the Devil’s Kettle and watching Lake Superior for any sign of their trinkets, but maybe there are other explanations. If you happen to be traveling, say, somewhere in Eurasia and stumble across a geyser that’s surrounded by pingpong balls, logs, and even a car that locals are reported to have pushed in one night years ago, you might want to call a geologist in Minnesota. You may just have solved the mystery of Devil’s Kettle Falls." - Mother Nature Network