So what is Geocaching? 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 containing a logbook and "treasure," usually toys or trinkets of little monetary value. Today, well over 350,000 geocaches are currently placed in 222 countries around the world, which are registered on various websites devoted to the sport. According to Geocaching.com there are 55 Geocache sites within a 10 mile radius of Mammoth Lakes (Zip Code 93546). Caches are located at points of historic interest, close to hiking and biking trails, some are even placed on Mammoth Mountain or at other high altitude locations which may demand a little more endeavor to find.