Not that I'm in the market, but saw this product recently. Can be used in salt and fresh, as well as having a release mechanism to transport a lure out to fish. I'm surprised they are saying that it will survive salt, but with all that electronics and close tolerance fits, it's hard to believe.
According to the specs, you have a 16-18min. flight time on one charge. Also you wouldn't want to land in water that was very choppy, or around boat traffic, as it would tend to flip. The other thing is, you can't fish and run that at the same time, like you can with a Gopro, or other brands on a fixed mount or head harness. If I was a prof. photographer, or someone in the real estate business, it would be good to have.