This cache isn't actually on the very short Trail of Two Forests. It's on one of the many trails that go all over the forest from the same parking lot.
From the parking lot for the Trail of Two Forests select any dirt path and walk until you get to the coordinates for this cache. The paths go all over the place and there's no one way of getting to the cache.
But don't just stare at your GPSr waiting for the numbers to match up. Look all around you. It's a unique forest in that it is a former lava flow. 2,000 years ago Mt. St. Helens erupted and dumped lava all over this area. A very different kind of eruption than the recent ones.
No pencil so make sure you bring one to sign the logbook.