What is geocaching? 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 or ammo box) containing a logbook. Larger containers can also contain items for trading, usually toys or trinkets of little value. Geocaching is most often described as a "game of hig …