The Elven King looked at Bilbo with a new wonder.
“Bilbo Baggins!” he said, “You are more worthy to wear the armour of Elf- Princes than many that have looked more comely in it. But I wonder if Thorin Oakenshield will see it so.
Thranduil, the Elven King of Mirkwood, was a simple soul - suspicious in nature but quick to re-align his loyalties when circumstances dictated that the enemy or a greater enemy should be treated as an ally.
Thus this cache is a simple find, as long as you avoid touching the waters of the woods, and as long as giant spiders don't get you!
Ask Thranduil: Where is Bilbo?
Thranduil doesn't know where Bilbo is, but his best guess is that you should look for Smaug the dragon - he is bound to know where to look for that burgler! Thus look in Thranduil's cache for the west coordinates for GC2CA4V - Smaug.