A very simple and fun idea to entertain your kids during the summer afternoons.
For a summer fun you can build some very simple and fun floating swans. Cut some simple swan shapes out of 5 mm plywood, leaving a short tongue at the base. Then cut a round disk, taking care that the diameter of the disk will be at least as big as the whole swan shape, and then carve a mortise in the center to attach the swan to the base. Attach to the bottom of the base 4 bottle corks cut in half lengthwise for a better floating capacity. Paint everything with waterproof enamel. Then make some fishing poles with a wooden ring at the end of the line and you are ready to go!