There’s one aspect of geocaching greater than any other: the social experience.
While the core idea is to search for boxes and discover new locations, what makes geocaching different from fishing, painting or building airplane models is the community. Geocachers naturally have a unique online community that can only be compared to hobbies purely digital, such as computer gaming. But also a very strong social presence in real life as the result of events. Regular events are held all over the world, where anything from ten to thousands of geocachers meet to talk and share experiences.
And when caching, there’s always that excitement of “us” and “them”, them being the people unaware of what you are doing. Not being too obvious when searching for a cache in a crowded place is common sense. But the feeling of operating underground, where everyone around you is the “enemy”, is something Saturday night bowling can’t really give you.