Malfunction!
This is a "Cache & Dash" style hide on the side of the A470 between Coed y Brenin and Trawsfynydd. The best parking spot is next to the big, colourful bins near the GZ. I've given it just one star for difficutly, although a sign near to the cache indicates that there might be a localised GPS signal anomaly. I can therefore make no guarantee that your GPS will work near the GZ!
What has caused this strange phenomenon? Is it ley-lines, geo-magnetism, UFOs or ghosts of Roman soldiers marching along Sarn Helen? Please speculate in your log!