Do not go to the listed coordinates...it's very, very wet there. It's in the middle of the Oconto River! You will need to complete the Oconto Adventure Lab to obtain the proper coordinates for this bonus cache.
An Adventure Lab, with up to 5 locations, can be played in the Adventure Lab app on your cell phone. Each Adventure enables players to explore and learn through stories and interactive experiences. Unlike other geocache types, Adventure locations are virtual (without a container). The Oconto Adventure Lab will take you to five historically interesting sites. When you get within 20-30 feet, a question will be posed that can be answered at the site. Each site counts as a find when it is completed. The bonus cache does have a container though...it's a magnetic keyholder. The coordinates will be displayed for this bonus cache at the last site that you visit. Bring your own pencil.
Note: When the lab was first published, there was no bonus cache. For those cachers who completed the lab before this time and want the coordinates for the bonus cache, please contact me.