Kankakee River State Park is about an hour south of Chicago located in Bourbonnaise, Illinois. We camped here when we visited Starved Rock State Park and Mathissen State Park. Overall, the park is really nice. Our camp site was in the Hawthorne loop of the Potawatami campground. If you are pulling a larger camper, you may want to check out the Chippewa campground as the roads in the Potawatami campground can be a bit tight. The sites are secluded with trees on at least two sides of you.
As far as hiking goes, there is a paved hiking/biking trail that runs the length of the park which has nice views of the river and a cool suspension bridge that crosses Rock Creek.There is also sort of “hidden” trail. I kept seeing on maps that there was a waterfall, but I could not figure out how to get there. If you ask as the Visitor’s Center, they will give you a self-guided interpretive trail map. The trail is located across the road from the main park. I will warn you, its kinda a weird trail. It is not very long, but you walk through some forest area and then eventually you end up on a old paved road. You can see the waterfall from here, but when we were there the water was so high that it was not much of a waterfall at all, more like just a river =) If you do this hike, make sure to hike down the paved path towards the main road and then cut off through the grasses to get a peek at the cave across the creek.