The name Jórvík is the Scandinavianisation of Eoforwic, the 10th century Northumbria's capital, now known as York. The Danish Vikings first captured in Eoforwic in November 866, they were led by Ivar the Boneless who had made they way north after coming ashore in East Anglia.
At the stated co-ordinates is a mile post which contains information you need to find the cache which is located at N54 0A.BCD W001 05.8E
A=smallest number
B=twice the first digit in the largest number
C=half the number of characters in the smallest word
D=the sum of the digits in the largest number
E=add to the last three digits in the stated westerley co-ordinate the largest number on the mile post plus one.
You will need to make a note of the value for this letter, which can be found on the log, in order to find some bonus caches.
The container has a log sheet but no pen. If you feel inclined, then feel free to write your log with an alphabet theme - ? is also for.... or in any other alphabetic sense that inspires you.