We started at S43 34.311 E172 37.359 and followed the boundary fence to get to the waypoint.
The waypoint is located at an old army site that was dug out during WW2. We are told that the caverns were to be used as a military headquarters but was a location of scientific interest for studying the Earth's rotation. It used to be possible, for a small fee, to take a tour run by the council through the caverns. The equipment within, after many years trapped following the 2011 earthquakes, was retrieved in 2023.
The cache is located close by at S43 34.ABC E172 37.XYZ
A = number of letters in maker's first name
B = Month opened minus 4
C = 3nd digit of year opened - 4th digit of year opened. Divide by 2.
X = Number of countries involved x 2
Y = 2nd digit of day - last digit of year
Z = Digital root of year - digital route of day