Manseok Park is a large north Suwon park built around Manseokgeo, a reservoir created in the late 18th century during the work on Hwaseong Fortress. It is a good place for an easy walk away from the busiest fortress sights, with waterside paths, pavilions, fountains, and open space used by local families.
The park also has sports facilities and the Suwon Museum of Art nearby, so it works well as a slower stop if you are spending more than a few hours in the city.