Clues:

Go north on Hwy 42 into Kewaunee. At the intersection where Hwy 29 goes left, turn right onto Ellis Rd. and head east to the end of the road. Park in the circle.

Facing the water, go to the right bench (or at least the concrete base that is the only part that is remaining).  From the south end of the bench take 27 paces south along the upper part of the park (not the sandy shore).  Turn left and head towards the water and you'll arrive at a large slab of rock.  Look under this slab on its north end.  Don't be too spooked if you see the bones of a dead animal there.  Remove the asphalt and second rock to expose the "box."  Replace the box with the same rocks on top but making it look unsuspicious.

Before you set out read the waiver of responsibility and disclaimer.

LbNA Home