Overview:
This cache is modeled after ecrane’s 50 Challenges Challenge (GC1X067). With his kind permission, I have created this “mini” version, which adheres to all of the same guidelines about what qualifies as a challenge cache. And, once you’ve completed this 10 challenges challenge, perhaps it will have only whet your appetite for more. If so, you’re on your way to qualifying for ecrane’s much more ambitious version!
The cache container is a large ammo box. It also contains a large log book, so please feel free to take up as much space as you like. It’s slightly different than a regular-sized ammo box in that the top is not hinged. Instead, it has lever-locks on both sides of the lid. To open, release both lever-locks (by pulling up, just as you would do with the single lever-lock which fastens the lid of a standard ammo box). Then simply lift the lid straight up and off. Reverse the procedure to re-close. Please make sure that you re-fasten both lever-locks so the cache stays nice and watertight!
This cache is not hidden right along a main trail, but it’s not too hard to get to either. When we placed the cache, we found two decent routes into the area, each from different trails. One route comes in from above and the other from below. I have supplied the waypoints at which to leave each trail (see “Additional Waypoints” below), but recommend the “from above” approach, because finding and following the game trails is much easier. The “from below” approach, on the other hand, doesn’t really have a very well-defined game trail, but would save you a bit of climbing and a few steps. But please also note that we did have to avoid some poison oak coming from below and saw none coming from above. So it’s your choice. And, as always, please be mindful of rattlesnakes and ticks in our local wilderness areas!
Please note that the “5” difficulty rating on this cache is for meeting the logging requirement (half a point per challenge cache completed certainly doesn’t seem excessive!). The actual difficulty of finding this large cache, once you arrive at GZ, should be about a “1”. 
Challenge Caches Defined (an excerpt from the “50 Challenges Challenge” description):
So, what counts as a challenge cache? A challenge cache is a particular kind of unknown cache. Unlike a standard unknown cache, a challenge cache generally requires you to have found other caches--often some sort of achievement--to qualify for the challenge. There are exceptions--sometimes a challenge cache requires you NOT to find a cache: GC1E8DZ and GC2CVJW, for example, require you to have logged 100 or more DNFs!
General Info and Suggestions:
As with the “50 Challenges Challenge”, you are encouraged to select qualifying caches from the bookmark lists of shell1fish: U.S. Challenge Caches: States A-CA, etc.; or Doctor A: Doctor A's list of CA Challenge Caches (thanks, list creators!), although this is not strictly necessary. Selecting challenge caches from these lists simply makes it easier for you to be sure that you have selected legitimate challenge caches. Any cache which appears on one of these lists should be acceptable for this challenge. This would only change if the nature of these lists should change in the future, but that’s not expected to happen. If you know of another challenge cache that isn’t on their lists and you think it should be, please let them know, and let me know too.
You are also encouraged to use ten completely distinct challenge caches to qualify for this challenge (e.g. not to use multiple calendar challenges, icon challenges, alphabet challenges, streak challenges, etc.). But this is merely a suggestion and not a requirement.
Perhaps you are new to the idea of challenge caches and are looking for a place to start? Well, none of the following are easy, here are some suggestions that will certainly challenge your geocaching skills!
A few excellent local challenge caches that you may wish to consider are:
Santa Monica Mtns History Adventure (GC18DXW)
-- log the caches hidden in the Santa Monica Mountains during the first three years of geocaching
Spinal Tap (GC1C4Y4)
-- log all of the caches hidden along the Backbone Trail in the Santa Monica Mountains
Ventura County Quad Challenge (GC22CJJ)
-- log a cache hidden in each quadrangle of Ventura County
And some excellent non-local (but still in-state) challenge caches that you may want to try are:
Discovering & Logging California's 58 Counties (GCQ2VC)
-- log a cache hidden in each county of California
Well Rounded Cacher (The Fizzy Challenge) (GC11E8N)
-- log a cache of each difficulty/terrain combination, including at least one of each type of common icon
The Jasmer Challenge (Northern California Edition) (GC1GBC1)
-- log a cache hidden during each month since geocaching began
the prof's challenge (GC21JJT)
-- log ten caches which haven’t been found for at least one year
If you would like to find a lot of challenge caches, all in one place, there are “Challenge Alleys” in both Northern and Southern California. Each of the “DNF challenge caches” referenced in the preceding definition is from one of these “Challenge Alleys”. Below is another example from each one. To see the rest, go to the cache page for one of these challenge caches, and then click on the “Geocaching.com Map” link to see what else is in the area.
Example caches from each of California’s “Challenge Alleys”:
Traditional - California Challenge of a Millennuim (GC1E9H9)
-- log 1,000 traditional caches (located in the Northern California “Challenge Alley”)
100 Cache Challenge (GC2E64J)
-- log 100 caches in a single day (located in the Southern California “Challenge Alley”)
All of the preceding examples are in California. But that’s because this challenge cache is also in California. Challenge caches from other places are just fine to use as qualifying caches, too!
The Specifics (once again drawn from the “50 Challenges Challenge”):
- You must qualify for, find, and log 10 challenge caches to complete this challenge and qualify to hunt the physical cache.
- A puzzle cache where you need to put together information from other caches is not a challenge cache.
- For challenge caches in which the cache owner allows multiple logs for completing the challenge multiple times, each of those multiple finds DOES count for this challenge cache (but, again, you are encouraged to use 10 distinct challenge caches to qualify instead).
- Past finds DO count, so you may already qualify for this challenge.
- You can demonstrate that you have completed this challenge by listing the caches in your "Found it" log or by creating a bookmark list. (Other options MAY be possible by request.) Please indicate the qualifying caches' names, GC numbers, and the date when you found them.
- You must find the physical cache and sign the log, before posting a “Found it” log on-line. “Found it” logs which cannot be verified will be deleted. Sometimes cachers prefer to hunt the cache and sign the log before actually qualifying. After they later qualify, they post a “Found it” log. This has always struck me as backwards and a bit anti-climatic, so you are encouraged to qualify first and then go hunting the final. But this is also a suggestion, so if you prefer to do things the other way around, it’s okay. If you do decide to hunt the physical cache first, you are welcome to sign the logbook, trade swag, drop off or retrieve trackables, and post a note to the cache page. Any other visitors to the physical cache are also welcome to do this, as well. Logging progress notes or qualifying notes to the cache page, should you care to do so, is just fine too.
Have fun, and enjoy the wonderful and diverse challenges of geocaching!
Special thanks to crossbow spartan for helping me select the location and place this cache, as well as all of the great challenge caches that we’ve worked on together!