Turkey Path in is in Leonard Harris State Park is the Grand Canyon of Pennsylvania.
This is a fairly steep trail with many switchbacks, which makes it an easy hike down and a tough one back. But don't worry there are bridges and stairs to help you out. It is also family friendly, but make sure you plan on taking on the added weight if you have young children with you. We went with our 4 year old and I gained an extra 35 pounds on the way back up.
There are two waterfalls that are worth stopping at and hanging out around, especially during the summer. If you are a photographer, make sure you bring your tripod. I left mine in the jeep because I didn't want the extra weight. (Still upset about that decision).
Once you get to the bottom of the path you will meet up with the Pine Creek Gorge Trail. The creek is a nice spot to relax and regroup before you make the trek back up the path.
I highly suggest going here in autumn. The leaves colors are incredible.