ya, the shark would definitely be beached at that point. it wouldn't be able to move at all. and if you consider the moving water in the ocean, are you talking about 3 feet when a wave is rolling in? or 3 feet on calm water. if its 3 feet calm, the bear would be pretty far in if a big wave came. if its 3 feet with a wave rolling in, the shark would definitely be beached.