If there's only one thing we've learned as a result of our travels in search of caches, it's that Wisconsin is a beautiful place with amazing variation in landscape. From the rugged, waterfall draped areas of northern Wisconsin, to the ocean-like shores of Lake Michigan in Door County....to the river valleys of the southwest and the dunes of the southeast to the central flatlands.....there is much to see and appreciate just within our own state borders.
Wisconsin, being the cheesy state it is with those great big lakes on our northern borders, doesn't quite have nicely defined corners like some states to our west, or even our own on its southern border. For this challenge, the northern extremes will serve as your "corners," In order to search for and log this cache, you'll need to find five caches, one at the geographic center of our state, and one at each of the four corners. Here are the little troublesome details.
*Caches may have been found at any time. Archived caches will be allowed for the purpose of this cache, as long as the cacher found them while they were still active.
*All cache types, with the exception of events and CITOs, are eligible.
*The reference points provide the geographic "corner" needed. Any cache located within Wisconsin's borders within 20 miles according to the flying crow can be used.
*When logging your find, you can prove your finds in one of two ways: create a bookmark list of your qualifying finds, including this one, and note dates each cache was found...OR.. Simply list the qualifying caches with the GC number and the date found in the body of your "found it" log.

For you purists, here are the caches that currently meet the corner requirements, plus one conveniently located at the geographic center of the state. All finders will need to find the geographic center one, but the four corners can be anything within 20 miles of the listed reference points.
GCR83Z Northwest Passage
GCKF2B Water Tower Cache
GCQMJD PI Prairie's Chiwaukee Prairie on YST
GCVCPP This Is Not Paris France
GCPNJC At The Center of It All
If new caches are placed that challenge these as the extremes, feel free to use those. This is for fun, not a matter of national security! 
For the cache itself....it will be one of your easier 5/5s. Since you have to travel to the four corners and the center of the state to find this one, the difficulty is rated thusly, though the hide is much easier. The terrain, however, still requires a short paddle in the warm months. In the winter, exercise a little care, as there's an ice fishing village in the area. Most of all...have fun!
Park hours are from 6AM to 11PM.