At the published co-ordinates you will find an inscription in the wall labelled The Sea Swallow.
You'll need to visit the published coordinates and decipher the code using the inscription.
HOW DO I DO THAT ?
R=Row, W=Word & L=Letter.
For example, using the top line of this description: At the published co-ordinates you will .....
R1W1L1 R1W3L3 R1W4L1 would equal a,b,c and therefore 123
Use the cipher and the Sea Swallow inscription to decrypt the below and find the cache.
N 53° 55.R2W3L2 R3W4L2 R4W1L2
W 03° 03.0 R4W2L3 R1W3L1
Sumcheck,the decimals = 14.
The cache does not contain a pen, please bring your own.Lovely photos are welcome, but not of the cache nor the inscription.
Please replace the cache carefully.