I need to put up a post to support the cam in that area but you're right, I need to know what's there.
The holes above ground I can fill but I think I'm limited on what I can do for those at and below the waterline. I dropped a large brick in the hole dug into the pond bottom that goes straight down and it completely disappeared.
I also experimented with dropping a large smoke bomb in the dam (above ground) hole and then covered it to see if the smoke would come out another hole but we'll call that a failed experiment
