Hickory Hills Park has a mid 1900’s barn, pond, and secluded campsites along hiking trails.
Chichaqua Valley Trail is paved, crossing along an old railroad line with scenic views of the river.
Fort Des Moines Park has a small arboretum, playground, and trail going around the lake.
Winterset City Park has a lot of unique features, with a hedge maze to explore and the Clark Tower to hike to. The covered bridge in the park is interesting to cross, with lots of beautiful mature trees and trails to hike. There are two playgrounds, a few covered shelters, and a beautiful stone bridge as well.
Pammel Park has a lot to offer, with historic sights to see, extensive trails, a nature center, and the only highway tunnel in Iowa. Middle River runs through the park, with a ford providing perfect splashing for kids. There is easy creek splashing access here, you can see more specific details about how to get into the water in this post.