This is a letterbox, please don't take the stamp
At the posted coordinates you will find a trail head marker.
If the marker has a white dot the letterbox final is at N39 02.427 W84 07.398
If a purple dot then N39 02.345 W84 07.289
ODNR Permit EF-06-11-24
See https://coord.info/GCARY9Y for parking and trailhead info
Here's a great park map https://drive.google.com/file/d/1vN-M0wnOxctzyuZbwmqZ-M6wVak81Z9Z/view?usp=sharing
You are looking for a metal water bottle in the end of a small diamter log.