This cache is not at the posted coordinates. It is an Adventure Lab Bonus Cache. You must complete all five stages of the Highcliffe Beach Hike Adventure Lab in order to achieve the Final Coordinates for this cache. You will need the Adventure Lab App to find the stages.
You can find the Adventure Lab here: https://adventurelab.page.link/ZHne
or scan the QR Code 
There is a Bonus Number at each Adventure Lab stage. Plug those numbers into the coordinates below to find the Bonus Cache.
N 50° 44.ABC' W 001° 42.1DE'
If you choose to complete all five Adventure Lab stages plus the Bonus Cache in one go, you will spend about 1.5 - 2 hours on the beach (maybe less if you rush) and walk about 4 km if you take the most direct routes and do not linger.