I’m not wholly convinced that the same one. I ended up (and I apologise cos my memory is hazy) under a monument / signpost or something, convinced that was it, with some sort of reference to lettering.
Having subsequently actually found a nano, I’m happy to believe that I was looking right at it and didn’t see it, mind.
What is it, in a nutshell? Is it the modern version of letterboxing
That’s actually a nie way of looking at it. It’s like the old “dead letterbox” idea, but GPS coordinates are published. So you peg it into your GPS along with maybe a cryptic clue, and go hunting.
It’s custom to take something and add something (took toy car, added Gnasher badge) and some people have trackable “travel bugs” that get moved from cache to cache. But that’s not mandatory, signing the log is sufficient.