You can park at S 42° 31.434 E 171° 24.443 about 100m in, there is a Plan Table that shows you the lay out of the tracks the day I put the cache out I went to the left.
The track through native bush is well formed, but it is quite steep and narrow in places. Steep dropoffs from the track are NOT guard-railed. GPS coverage is non-existant in a couple of places due to the terrain and high trees but will work close to the cache site.
The cache is a 3L Ammo Container, with a few swaps. When I placed the cache GPS reception was not great, trees and lots of rain, but when you get to the lookout that over looks the top side of the dam.. ( there are two lookouts about 100m apart the other one over looks the bottom of the dam ) so when you find the right lookout the cache is 10m behind you and about 5m of the track, it can be seen from the right angle.