Pond survey camera suggestions?

PHXAZCRAIG wrote:

I would like to know what the bottom of this pond actually is like. Is it mostly just silt-covered liner? Are there actual dead trees and bushes mucking things up?

If it is just a silt-covered liner, I would think there would be some obvious disturbance in the silt pattern nearby, unless it was quite deeply covered in silt.

I think think the liner is quite clear. In fact, I see some folds in it that never flattened, and there are probably a few fishing lures hooked into the liner over the years (although they'd make very slow leaks, not sufficient to explain this).

Unlike the upper pond, the lower one has no shallow area, and most of the runoff coming into it is from the upper pond, so nothing really drags silt in. It also doesn't have a ton of willows around it shedding leaves into it. I think it's just got some random branches in it that fell in and sank, not much of that, but not nothing.

I have to say that the CHASING Dory Underwater Drone seems like a really great answer, as well as a fun toy to have around. I'd just have to convince my wife to spend $500 on yet another toy. 

BTW, I probably could drain the lower pond pretty easily, but I don't want to lose the fish population. I could probably do something collecting the fish (net? electro fishing?) and temporarily overcrowd the upper pond as long as I supplement the oxygen level. Of course, when I say "easily" I should note there's still close to a million gallons of water in it -- it would take blocking the overflow in, pumping it out for a week, and praying for no rain in that time. All of which is do-able.  Honestly, this might be the right answer because then we could reshape the pond a bit to make it more effective....  Not a cheap answer, but maybe right?