I'll bet that subject line catches some attention... Sorry to disappoint, but I don't actually plan to try flying my Phantom underwater. As I mentioned in another post, I do need to run a search mission in which I'm looking for something underwater. The depth of the water varies, but during a practice flight the other day, I flew at 10m shooting 4K video and had pretty decent visibility of the bottom of the lake. I even managed to see a few fish... But I have a very large area I need to cover so I'm hoping some of you might have some advice/suggestions on how to it do it with maximum efficiency. Obviously, the higher I fly, the more area I can cover in a single frame/shot - but how high can I go and still see the bottom of the lake. Would pictures or video be better? Are there any camera settings that would be better than others for ensuring that I focus on the lakes bottom instead of its surface? As of now, I think I'm going to have some trial/error ahead of me - but with your suggestions, I'm hoping to limit my trial and error to a single flight.