De Muy is a freshwater dune slack — a damp, sheltered hollow between the dune ridges — that functions as one of the most important breeding sites for spoonbills in the Netherlands. The reserve is just north of De Koog, reachable by bike in fifteen minutes. A small observation hut gives views over the open water and reed beds without disturbing the birds.
The reserve is closed to the public during the breeding season (March to July), but viewpoints remain accessible and the spoonbills are clearly visible from outside the fenced area. Outside breeding season, the wetlands fill with ducks, grebes, and wading birds moving through on migration. The combination of De Muy and De Slufter in a single afternoon's cycling makes for exceptional birdwatching even by Dutch standards.