You name it I’m sure you can find it at Hartman Creek. From swimming area fishing hiking trails. My favorite camping ground even when was a kid.
Great camping and there are some areas that you can group camp. Great place to take in views of Horicon marsh. The trails and play ground. Just a awesome place to get out and relax 
I’d say Derge Park is one of those get out of town but not of town parks. It right next to Beaver Lake. Witch is a great fishing lake. Or just to kayak. The boat launch is right across the park. There are not a lot of sites inside and out side bathroom with showers
We when’s when it was very hot. And raining. There was a small general store that had food and ice cream. And a small game room. They even have a pool.
Yellowstone Lake is great for hiking and fishing. They even have a swimming area. But a must is the small ice cream shop that has even lunch menu. The wife and I just loved the small town that was a drive away as well