The Cache is NOT at the posted coordinates.
This is a bonus cache for completing the Adventure Labs: "WI YST AS: Hudson to Roberts Part 1 and 2".

The Wisconsin Portion of the Yellowstone Trail Adventure Lab Series , over 150 stops, was inspired by members of the Wisconsin Geocaching Association. The 10 stops here in this Hudson to Roberts Part 1 and 2 segments can be done in any order. There is also a mystery BONUS cache, located here in Prospect Park in Hudson.
The historic Yellowstone Trail was established in 1913 as a cross-country route for automobiles - the first of its kind - stretching 3600 contigous miles, connecting the east and west coasts. It was the highway that opened America's northwest to auto tourism, and helped birth a new phrase: "road trip." It allowed the average family to experience the country, its geography, and its culture from coast to coast.
Construction and maintenance of the route, originally dirt and gravel roads, was largely done by local communities. With the advent of the interstate highway system in the 1930's, the Yellowstone Trail fell into decline. Today the trail is fragmented, with the Wisconsin section being one of the more complete and cared for segments of this once great route across America.
Although not required, please feel free to upload your (non spoiler) pictures from your adventure and tell about your experience in your log.
Your adventure can begin after downloading the Geocaching Adventure Lab mobile app from Groundspeak (geocaching.com). To find this app, scan the QR code's down below.
Hudson to Roberts - Part 1 Hudson to Roberts - Part 2
(below) (below)

Geocaching Adventure Lab caches can only be found with the use of a smartphone or tablet using geocaching.com's free Adventure Lab app. After completing the Adventure Lab cache, the app gives you the coordinates for this mystery bonus cache.