Some years ago my wife was strolling along the lake shore and noticed a sudden streaming which disturbed an otherwise calm surface. I went to that spot later on, and found this; imprinted on the lake bottom. The depth was ~3 meters.
The tracks are 60 centimeters apart and 6-7 meters long, connecting in a perfect half-circle at one end.
It does not seem to be caused by any natural means I can think of. My guess is, it was left by an "Unidentified underwater Object", though Im open to suggestions...
So, what do you think?