I have 2 idea's for the pond i am building in my back yard. My dad has two old boats out back one of them is about 16 feet long, i was thinking about taking one of them and completly stripping it out on the inside and making that into a pond. I would bury the boat far enough in the ground so it would look like its sitting in water. Then plug the boat and fill it up with water getting a pump and filter for it also of course but i don't think i would be able to run a waterfall with it or have a place where the water runs through rocks is that necessary or does it just help? i would have everything hidden under the water the pump hose and the return hose do you guys think this is a good idea? the other idea i had was to build a wooden octagon frame out of some kind of wood then digging it out about a foot to two feet below ground and having the frame about two feet above ground then putting a pond liner in it and adding a filter pump and waterfall. Which idea do you guys think would be more cost effective i would want either just koi in it or maybe largemouth bass with bluegill.