This stone structure at the north-western end of Woy Woy Bay, now little more than rubble in parts, is something of an enigma. I'm surmising it was originally used as a jetty, or at least a means for people to come ashore without muddying their shoes, yet the water at its far end is less than half a metre deep at high tide, making it unsuitable for any decent-sized vessel. But perhaps the bay wasn't as silted back then, or maybe they dredged a channel, who knows? Also unknown is its purpose. Old zoning maps show an isolated allotment here but most of that has been subsumed by the national park and the remainder, including GZ, is now zoned Recreational Waterway.
Just to the north-east of the jetty, in amongst the mangroves at reference point R0, is a line of wooden posts that might have been part of an associated structure. To the north alongside the creek are some clearings that may once have been camping sites, or even a fairground with Woy Woy's gentry arriving by paddle steamer for a day of frivolity:
To find where I've hidden the cache, study this imagined scene to, well, find the cache and reveal the coordinates. Once you've solved the enigma, you can launch your own paddle boat from the little beach next to the public wharf in Bassan Street. The jetty is about a 1.5km paddle from there. The checker will provide some additional guidance.
I recommend only attempting this cache right on high tide otherwise you'll have a bit of a trek through oozy mud and oyster shells which you might not enjoy. King tides should be avoided, though, as the jetty and much of the estuary will likely be underwater. Allow time to explore the area and see if you can piece together any of its history.
Note that the tides in the bay lag a couple of hours behind the ocean tides, but the tide times for Gosford (http://www.bom.gov.au/australia/tides/#!/nsw-gosford) should be fairly close.
The cache is a 380ml Sistema. A pencil is included but bring a pen just in case the previous finder broke it or dropped it in the mud. When rehiding, please make sure to conceal it completely with the camo rock in case one of the visiting gentry should wander by while looking for the Ferris wheel.