The Devil's Kettle Waterfall

One mysterious phenomenon on the Earth is a place called The Devil's Kettle Waterfall in Minnesota, USA. Scientists still don't know the source of the water and where the water is actually going to. There are two different bodies of falling water - one is falling into one body of water, and the other one is falling straight into a natural hole in the ground. Nobody knows where the water leads. People have thrown sticks and other items into the hole. The items seem to disappear and don't come out the other end. What a mystery this is! Scientists have even put colored dyes and tested the water downstream, but the chemical dye was undetected down below.