The cache is not at the posted coordinates. If you choose to go there you will be swimming.
This is a bonus cache for completing the 'Old Poole' Adventure Lab cache.
The bonus cache location information is contained within the adventure lab experience itself.
Click on the link below to open this adventure in the Adventure Lab mobile app.
https://labs.geocaching.com/goto/ptal2
Once the lab cache has been completed you will have 5 numbers ( A,B,C,D and E) - with those you will be able to calculate the final location.
N50 42.(B+D)(A+B)(C-6)
W001 59.D(E-C-B)(A+B+2)