Officially, the Grandma Gatewood Trail in the Hocking Hills is about a 6 mile one way hike that begins at Old Man's Cave and ends at Ash Cave. Because I don't normally hike the route with a shuttle, I turn it into a 12 mile out and back, starting and finishing at Old Man's Cave. If you can be on the trail by 8AM or sooner, you won't have to deal with the crowds and it is a really fantastic hike.
Everytime I hike the trail, I always enjoy this little tunnel that you travel through en route to Cedar Falls from Old Man's Cave. I imagine that Grandma Gatewood, the first woman to thru-hike the Appalachian Trail (in a pair of Keds with a homemade knapsack no less), spent quite a bit of time in this location, hence the name. There is some really fantastic geology at work here as well, namely the slump block and the erosion that has caused this outstanding passageway but I won't make you deal with that for this cache.
To get credit for this cache, take a picture of the tunnel or the entrance to the "tunnel" as I have done on this cache page and then take a second photo as you are entering or leaving the tunnel. It's a little bit of a hike to this location, which is why the terrain rating is what it is. Enjoy!