This cache is located off of the road that leads to Ice Cave. When near GZ go around the road closed barrier on the way to Ice Cave. You will see a mountain bike trail to your left; stand there and look ahead and slightly left for a completely hollow tree held upright by 7 smaller trees This area could be a little wet as it is below a ravine. If coords are jumpy use the Hint. Peanut butter jar.
If you are doing Adventure Labs, one of the stages of the Adventure Lab "Decorah: A Driftless Adventure" is nearby.