Aliens? Take yer pick... Mystery Cache

This cache IS at the listed co-ordinates, but you will need a tool (which is not provided) to access the log.

The location lends itself to cache-and-dash, but you need to take the time do some work at GZ. 

Congratulations to Aquachippy for First to Find, 31.08.13

One of our visitors has left evidence behind. Can you find it and - having done so - gain access and sign his guest book (which is safely locked away) to prove it?

The difficulty rating refers to the fact that you will need to bring along a tool and use some skill to complete the task. You do NOT require physical strength or brute force; please do not damage the cache. You are looking for a micro cache in a larger container. It does not contain a pen.

Since gaining access to sign the log is an integral element of this cache, you must sign the log to claim the find: he'll be watching....