From the Park's parking lot, start your walk at the trailhead at N 48 01.098 W 122 48.328. After a short walk, take the trail to the left at N 48 01.201 W 122 48.305 and then another left onto a smaller harder to find trail at N 48 01.070 W 122 48.775. At this point you are basically walking through the woods. The cache is in plain sight once you get to the cache coordinates.
You problably will recognize very quickly that the dense forest significantly restricts your GPS reception. My unit (a Garmin 12) was luck to capture 3 or 4 signals weakly most of the time. All readings are probably +/- 0.005'.
The cache is in a large, camouflage painted ammo container. The cache includes: a new Navy Ship's ball cap, a Santa Pez dispenser, some pictures, some MacWorld Convention memorabelia, plus more.
I hope you are able to find this one OK.