To find this cache, you will need to exercise some skills in
using your GPS & take a moderate walk (less than 2km) You
may get muddy feet and please use your good judgement
whether to do this cache or leave it for another day if there
happens to be an equestrian event on. Most days the park is wide
open, with dog-walking muggles scattered about
Go to the listed coordinates for your starting point; Be sure to
clear your tracklog & start fresh, because from here on you
must enter & go directly to each consecutive waypoint.
As you progress, your tracklog should draw a picture that will
reveal the location of GZ to you.
All waypoints will be S35°44._ _ _ and E174°16. _ _ _ so you just
need to change the last three digits for South and East which you
will find on a tag at the start and at each following waypoint, in
this format: 123/456 ie; your waypoint would be S35°44.123
E174°16.456
The last tag will have two sets of numbers; the 1st being the
endpoint to finish your "drawing", and the 2nd set for a
nano/micro(dog ID barrel) with an additional hint -ROT13
encrypted!( standard geocaching.com hint encryption 
) in case you need a little extra help
with finding the cache.
Happy Trails & Caching 
Now go Make Tracks!
Many Thanks to Clan Riffster for the concept & advice!