This is a Mystery Cache, so the cache is not at the listed coordinates, go there and all you'll get is wet. To find the actual coordinates you will need to do the 'Blenheim - Remembering Our Past' Adventure Lab Cache and get the information as you obtain each of the four waypoints.
As you successfully progress through each of the sequential waypoints you will receive hints to make the final find easier. You will find the cache at S 41 30.ABC E 173 57.DEF.
B.Y.O.P.
Update 17 July 2022: Note this update supercedes some information in the previous update. There are two information boards within the 20m geofence for the final waypoint of the Adventure Lab Cache that will give you the correct information to answer the final waypoint question. If you take the distance and bearing off the wrong information board, you final coordinates will be out. To ensure you select the correct information board, the final one is manufactured in the same format as the previous three Adventure Lab cache waypoints.