Pretty cool, even if they are controlling it a bit:

Parks Canada caches are located in publicly accessible areas and are accessible from trails and/or roads. Instead of containing trade items, caches contain messages that reveal interesting often unknown aspects of the area where they are located. Parks Canada aims to encourage geocachers to share their enthusiasm for a particular park, site or marine conservation area by recounting a tale, a personal experience, knowledge or an anecdote for other participants to find.

(Également disponible en français, naturellement.)