I finished a trip report in the latest Boundary Waters Journal magazine and also recently read another one on a different message board and both had accounts of this mysterious loud splash in the water.  The authors and their trip mates were stymied and one suggestion was that it was a large fish feeding on the surface.   :)  Both accounts had it sounding like a "bowling ball or large rock being dropped into the water".

My first experience hearing this mystery noise was on my first solo in 1984.  I was a very apprehensive 24 year old and remember hearing it after dark one evening as I lay in the tent. It's a long time ago and I don't remember my emotions so let's just say I was "concerned".  Ok, let's say I was scared $&*% less. :D

Later that trip I happened to come upon a swimming beaver and he demonstrated how he produced the sound.  That big flat tail makes a helluva wollup!  So, does anyone have stories of their first time?  I had fun with my teenage nephews when they heard this sound one night in 2015 on their first trip.  What are uncles for?  ;D ;D