Aquanox
I got the idea for this geocache while hiking around Saltese Wetlands. I highly recommend making the loop and finding the other caches and adventure labs. As a matter of fact one of the stops on the "Saltese Creek" adventure lab will find yourself right here at this cache site which inspired the name of this little creation. I've added north and south parking coordinates depending on how adventurous you are feeling. The north coordinates will put you about 300 feet from GZ where you'll have to cross a grassy field and enter the Saltese Wetland through a public gate (also annotated as an additional waypoint). The south parking coordinates are a little less than 1/2 mile from GZ, but you can grab a bonus geocache, Saltese Flats bridge to nowhere, while in route.
I'm listing this cache with an elevated difficulty rating as it might be more challenging to find than your ordinary geocache. I gathered the coordinates using a Garmin Rino 650 and averaged the waypoint for over 5 minutes until the device was 100% confident so they should be SPOT on. No need to reach or climb inside the structure. Also, no need putting yourself at risk of falling in the water by searching on the back side of the fence. You will need to bring your own writing instrument and perhaps some geocaching tools of the trade (TOTT - ie. tweezers). Sorry, no hints until somebody is first to find (FTF).