CAVEAT: This cache is intended for experienced hikers/bushwhackers who welcome a challenge. The hike isn't bad... approximately 1.0 mile one-way with an elevation gain of 500 feet. But then you have to scramble up a rocky crumbly muddy hill, gaining 200+ feet in less than 0.1 mile, and follow an unmaintained old trail with a fair amount of exposure to the cache location. If you are not in good physical shape, or if you have fear of heights or exposure, then DO NOT attempt this! Leave the kids and dogs at home for this one. Also, I do not recommend attempting this during wet conditions because the scramble would be quite dangerous. I think it's worth the effort (and not just for the cache), but only you can gauge your physical ability. Although I hate to resort to legalese, I will not be held liable for any injuries resulting from any attempts to find this cache.
If you look for this cache, you will be rewarded not only with a cache, but more importantly a private viewpoint of the upper tier of Upper Latourell Falls. Wear long pants and sturdy shoes/boots.
Just after you cross the footbridge, on the west side of the creek you will see the beginning of an old trail just above and parallel to the official trail. Take that trail until it ends at a rockslide, and then carefully make your way up the hill. Look for the old trail as you climb uphill. You do NOT need to climb all the way to the top of the hill! When you rejoin the old trail, take it (to your left) and backtrack toward the waterfall.
You are looking for a small plastic lock-and-lock container. There is room for small trading items and trackables. After you find the geocache (which will be easy), continue beyond it to your private waterfall viewpoint. Approximately a century ago there used to be a footbridge crossing the creek here. Enjoy the view... you've earned it! And look down at the hikers on the "real" trail... they look pretty tiny from up here, and they have NO IDEA that you are looking down at them!
Huge congratulations to geojerry7 for being FTF!