The published coordinates are NOT the real location of this cache, but they will give you a feel for the terrain around Ground Zer0.
If you look at the boundaries of the Blue Mountains National Park, just south of the Leura Cascades there is an unusually shaped section of the Jamison Valley that is not national park. This in fact is where the sewage of Katoomba and Leura used to end up; via pipes that went down the hill next to the Leura Cascades, to a treatment plant in a clearing at the base of the escarpment, and then out into the Kedumba creek. Since this area is not in the national park, I thought there would be some interesting spots to stick a geocache.
Then I went there. It was really not much fun.
To be perfectly frank, the scenery in this part of the valley is not spectacular; some of it is pleasant, but none of it is commensurate with the effort. I was surprised at how much signs there were of human activity in the area. Some of it (especially near the access road) may have been SCA or NPWS workers, but I saw evidence of several previous bush walking parties having gone through as well, I reckon they may have been a bit deranged.
On my first trip out to GZ, it took about 4 hrs there and back.
The second time I tried to get to GZ, I was having such an unpleasant time with the terrain, I gave up when I was about 750M from my destination.
Unfortunately I had left something at GZ on my first visit that I now needed back. So off I went again. This time I picked a better line, and my round trip took 3 hours, of which I only really hated about 15 minutes. On the way I set up a geocache so anyone else who wants to can share the "pleasure".
The most unpleasant bits of the terrain down there are the apparently 'open' sections, which are strewn with slimy boulders and slippery dead trees, all hidden under thick ferns and stinging nettle. The chances of a stumble, resulting in a busted ankle or other limb, are very high. And if something like that did happen, your chances of getting back to civilization unassisted would be pretty slim.
If you do your research, you may find a way in that minimises the traversal of the worst terrain, but you can't avoid it entirely. In fact the '5 star' difficulty relates not just to finding the coordinates, but in finding a reasonable way to get to them.
There are several hundred meters of elevation change involved in this cache, but no exposed sections or technical sections, unless you intentionally choose a route that involves that. I would strongly recommend some hiking poles for keeping your balance in the off-piste sections.
You can check your answers for this puzzle on Geochecker.com.
Congratulations to WebGuy and Wingnut on their FTF - the path they chose is definately not for the faint-hearted