My kids fish there too...they've also been to the place under the waterfall that you're talking about. Maybe you can bring your own kids here someday! :-)
I caught my first fish in that lake when i was 9! If you go to the end of the lake and go under the waterfall there is a secret room under the waterfall where me and my friends used to play !!
Oops!
Oops, you forgot something.