The cache is not at the listed coordinates.
There is, however, a very nice bridge that happens to be the starting point for the Frankston Waterfront Wander Adventure Lab which, once completed, will reveal the necessary information to locate the cache.
Frankston Waterfront is one of the most recognisable features of the area and plays host to several major events year-round as well as providing an outdoor precinct for locals and tourists alike to visit and enjoy.
The Waterfront of today was largely developed between the mid-2000s and late-2010s, with features such as the Landmark Bridge, southern boardwalk extension, Visitor Information Centre, playground (as well as its subsequent renovation) and several public art installations all added during this time.
This Adventure Lab focuses on the art and sculptures of the foreshore, highlighting five in particular that must be identified to find each location's answer.
To locate this bonus cache, you must first complete the Frankston Waterfront Wander Adventure Lab on Groundspeak's Adventure Lab app.
You can find it by clicking this link, scanning the QR code below or looking for the Frankston Waterfront Wander pin on the Adventures app (which is at the same coordinates as the pin for this mystery cache).
When a location is successfully answered, a journal entry will appear with a congratulations message alongside some clues. Completing all five locations will unlock all the clues you require for this bonus cache.
Once you have all of your clues, ensure the letters are in the right order (it's quite on theme) and substitute their corresponding numbers into the following coordinates:
S38 ??.??? E145 ??.???
Feel free to use the checker below to confirm your coordinates, it'll also give some helpful hints as to the nature of the cache hide.
Enjoy your waterfront wander and have fun!
Congratulations to Steak_286 for being First To Find!