geocaching

 geocaching  is hiding and locating containers at specific geographic coordinates using GPS.

The dominant silo providing services to the geocaching community is Geocaching.com. Other sites include terracaching.com and opencache.uk. Geocache logs could be considered checkins.

Brainstorming
Besides the checkin information, I would also suggest another property which indicates whether you have found or did not find the log. Something like p-geocache-log-type where value is either 'found' or 'not-found'. With this property, we can also explicitly set a post to 'geocache' instead of a checkin only.

is currently exploring this with Indigenous for Andoid which has a Geocache form posting found geoaches on his site at https://realize.be/geocaching. Minimal context is also parsed from the geocaching.com site and wrapped into 'u-geocache-of'. The data for the checkin comes in by passing all info into the Geo URI, see https://indieweb.org/Micropub-extensions#Location_checkin_information

Example: https://realize.be/cache/1344

Parsed by pin13.net: http://pin13.net/mf2/?url=https%3A%2F%2Frealize.be%2Fcache%2F1344

Notice the proposed 'geocache-log-type' property parsed there.

PESOS to WordPress
has implemented a WordPress plugin that performs manually-initiated PESOS from a variety of geocaching websites including Geocaching.com and opencache.uk and is selfdogfooding it on danq.me: blog post | source code