A recent survey shows nearly five percent of geocachers are 18 or younger, that’s still nearly a quarter of a million geocachers. – SOURCE
Geocaching is an outdoor game like hide and seek. To play you need a Global Positioning System (GPS) receiver or other navigation technique to find containers, called “geocaches” or “caches”. The caches can be anywhere in the world!
You don't always know exactly what your looking for – but normally it's a small waterproof container containing a logbook. In the logbook, people enter the date and sign it with a code name. You must place the cache back exactly where it was. Geocaching is like treasure-hunting and waymarking.