Over and under achievement
This achievement would mark when a single hashpoint is reached at substantially different elevations. As an example, I awarded myself this achievement (as a gratuitous ribbon) for reaching the 2010-08-05 45 -122 hashpoint both on an elevated freeway ramp and on the ground, several dozen meters below. Other examples could include the top and bottom of a cliff with a substantial overhang, a balcony and the sidewalk beneath, different floors of a tall building, or the base and upper limbs of a substantial tree.
There could be occasions when this would overlap with an Air Geohash or an Underground Geohash, but it is a somewhat different and, I think, noteworthy feat.
This is the "gratuitous ribbon" I made myself:
|Michael5000 earned the The Over and Under Achievement|