Administered by King County, Marymoor Park really is a beautiful area of wilderness. The park is a huge expanse of overgrown fields, alder woods, marshes, and a bubbling river. The large dog run gets crowded on weekends. Head for the running trails, horse paths, tennis courts, velodrome and climbing wall. Take kids on the interpretive nature trail, or to the playgrounds, or to the community garden plots. The whole area can fill up with cars and people and still feel empty.