Did you think that only theasure maps are for kids? Think again!
Geocaching is an outdoor activity in which the participants use a Global Positioning System (GPS) receiver or other navigational techniques to hide and seek containers (called "geocaches" or "caches") anywhere in the world. A typical cache is a small waterproof container (usually a tupperware container or ammo box) containing a logbook.
Many caches are placed on historic or in other way interesting places. Are you interested in learning history or about a place, geocaching is a good starting point for you. An example can be the Keplar star, something build many years ago.
You can read more about it on their own homepage www.geocaching.com. You can also read more about GSAK, an application that I use to manage the geocaches.
You can read more about my finds here.