Geocaching is an outdoor treasure-hunting game 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 or ammo box) containing a logbook and "treasure," usually toys or trinkets of little value.

The only rule you'll need is to make certain you leave something in the cache once you have found it, and not to place caches in delicate, historic or archaeological sites.