The posted location provides a great outlook to Christchurch, but there is nothing hidden there. In order to obtain the coordinates for this cache, you will have to complete "Hills of the Port" Adventure Lab: https://adventurelab.page.link/vezx
Each completed adventure location will reveal a piece of the final coordinates. Put them all together and find the bonus cache!
The cache is a 1L cylindrical container, hidden on one of the peaks of the Port Hills, not visited during the Adventure Lab. It is a walk or a bicycle ride to get to the final, there is no motor vehicle access.