Here is a great trail in the Castlwood State Park! You start off on some nice mellow trail folowing the creek banks over to the Lone Wolf shelter where you are greeted by a 9% grade, half-mile climb! At the top of the climb it gets a little easier, but you're still climbing for a little over a half mile more.
You then come to the castle in the woods. Round the castle and you start back down in to the creek valley below. There are a couple of logs to get over on the downhill and an armored drainage crossng swithchback at the bottom, then back into some more creek bank running!
You'll come to a section in the trail where you'll have to cross the creek. There is about a 8" or 10" drop into the creek and there is usually around 6 to 12 inches of water 15 or so feet wade through and you're back into the parking lot.