Walnut Woods State Park is a tranquil destination for anyone seeking the outdoors not far from the state’s capital city. The park is home to Iowa’s largest stand of black walnut trees, with one of the park system’s finest examples of a 1930s CCC-era lodge. Nearby, launch a canoe at the Purple Martin Water Resource Area or observe the purple martins that inhabit the area. These fascinating birds have their own unique establishment near the lake.