A local pond in my area of NC has a large, metal fence/kennel type box anchored to the land and stretches into the water almost halfway. It is open at the water so the ducks can swim in. Sometimes the opening is submerged; sometimes it's above waterline, depending on the rainfall. Waterfowl swim in or under, to get inside. It's really quite amusing to watch. There is a man-sized gate on the rear land side for feeding and occasional cleaning, I presume.
