This is a photo from the town I grew up in. There’s a secret air filled chamber underneath this tower. Kids would dive off of it and swim into the underwater entrance. This pic is from 1973. I always heard stories about it but I never experienced it myself. Here it is today.
I used to swim up into this air pocket! So much fun and not so scary once you do it…. You can also lay flat in a canoe and slide it under the dock right next to this tower, and canoe all the way to the sewer drain in the parking lot! You get to sit up eventually. Oh to be a kid again.