William O'Brien State Park, Minnesota, United States.

William O'Brien State Park, Minnesota, United States. Main office.

William O'Brien State Park, Minnesota, United States. Restrooms/Showers in the Savanna Campground.

William O'Brien State Park, Minnesota, United States. Restrooms/Showers in the Riverway Campground.

William O'Brien State Park, Minnesota, United States. Trail along the river.

William O'Brien State Park, Minnesota, United States. Trail along the river.

William O'Brien State Park, Minnesota, United States. Beach area.

William O'Brien State Park, Minnesota, United States. Beach area.

William O'Brien State Park, Minnesota, United States. Horseshoes by the beach.

William O'Brien State Park, Minnesota, United States. Horseshoes by the beach.

William O'Brien State Park, Minnesota, United States. Volleyball near the beach.

William O'Brien State Park, Minnesota, United States. Pavillion near the beach.

William O'Brien State Park, Minnesota, United States. Bridge over a hiking trail.

William O'Brien State Park, Minnesota, United States. Bridge over a hiking trail.

William O'Brien State Park, Minnesota, United States. Flowers.

William O'Brien State Park, Minnesota, United States. You cross this railroad on the hiking trails.

William O'Brien State Park, Minnesota, United States. Old shack on one of the hiking trails.

William O'Brien State Park, Minnesota, United States. Map of the park and hiking trails.

William O'Brien State Park, Minnesota, United States. View of the prairie from the hiking trails.

William O'Brien State Park, Minnesota, United States. View of the prairie from the hiking trails.

William O'Brien State Park, Minnesota, United States. Visitor Center.