This won't make a lot of sense to anyone who has never read the Chronicles of Amber by Roger Zelazny and, really, for people not familiar with Geocaching. For the first one, well, it's almost too complicated to explain... in the Amber books, there are really only two real worlds: Amber and The Courts of Chaos. In between them are the shadows, including our Earth. Royals from Amber can walk the Pattern to travel freely through the shadows. Which is probably enough to explain the photo... but the books are classics and if you haven't read them, I recommend giving them a try.
As for Geocoins, they're large coins that have individual tracking numbers on them and are designed to move from Geocache to Geocache and be tracked along the way. My husband loves designing them and for his very first coin, he did one called "All Roads" (as in "All roads lead to Amber"), with the Pattern on one side and a very Amber-like design on the other. Here's a photo of the Pattern side of the coin, held by my husband to give it some scale.
And for those who might be curious, here's a photo of the obverse: