Hash collision achievement
From Geohashing
Visit a geohash and, either through prior knowledge or pure chance, find a geocache on site of the hash. To count as being at the geohash site, the geocache must lie within sight of the circle of uncertainty of your GPS around the geohash coordinates. Placing a cache yourself does not count, unless you placed it before the coordinates of the geohash were announced, but you can place one that helps other geohashers later in the day win this award.
Honorable Mention
A geocache discovered within one kilometer of the geohash wins you the honorable mention.
Proof
For proof, the contents of the cache should be photographed, particularly if it has a logbook; feel free to sign it. A link to a geocache site advertising that location would also be good.
