There is no widely accepted definition of what it means to reach a geohash, and it is generally up to each participant to come to their own definition and decide whether or not they reached a given point.
The core essence is:
- You must get yourself close to the given coordinates.
-* You must get there during the given 24 hour time window.
Some definitions used by various community members at different points:
- Get close enough that the zone of uncertainty of your GPS device includes the point.
- Get within a few metres of the point.
- Imagine that while you are there, an infinitely tall pole, 1 metre in radius suddenly appears at the exact point. Are you at least 50% confident that you would be able to touch it? (Stevage's definition). (This means that for points in open fields, it is less important to navigate precisely to the exact point, but in places where obstacles block movement, it is more important to ascertain exactly where the point is and to get to it.)
In the early history of geohashing, when a point was deemed inaccessible, "alternative meetup" locations were proposed, and success sometimes claimed by reaching those. This is generally not considered to meet the criteria for "success" these days.
At times, the use of the word "success" has also been contested, which is why terminology such as "coordinates reached" is often used. The argument being that an expedition that does not reach the coordinates might still be a "success" in other ways.
