Geocaching is a real-world, outdoor treasure hunting game using GPS-enabled devices. People hide geocaches around the world and leave their coordinates online for other people to find them using GPS devices. People may leave behind objects in geocaches for geocachers to discover.


On May 2nd, 2000, the U.S. government disabled Selective Availability1, which was an intentional degradation of public GPS signals to allow optimal performance for national security use. The shutdown of Selective Availability instantly improved the accuracy of GPS receivers around the world. As a result, many GPS enthusiasts began thinking of ways in which the new technology could be used.2

On May 3rd, 2000, an enthusiast named Dave Ulmer3 hid a container in the woods near Beavercreek, Oregon, near Portland. He shared the coordinates of the location of the container (N 45° 17.460 W 122° 24.800) online and within a week, others began doing the same thing.

A mailing list called “GPS Stash Hunt” was created to discuss the emerging activity. Several names were suggested to replace the name “stash” due to the negative connotations associated with the word. One of these suggested names, “geocaching” was first coined by Matt Stum on May 30th, 2000. This name was chosen because of its meaning.

Geo, the prefix, describes the global nature of the activity and its relevance in GPS topics, such as geography. The word cache refers to a hiding place someone would use to temporarily hide items. Also, a memory cache is a computer storage that is used to quickly retrieve frequently used information.

How to go geocaching

  1. Register for a membership online
  2. Search for a list of nearby caches by entering your address or zip code
  3. Choose any geocache from the list and enter its coordinates on your GPS device
  4. Use your GPS device to assist you in finding the hidden geocache
  5. Sign the logbook and return the geocache to its original location

Some common rules/courtesies of geocaching

  • If you take something from a geocache, leave something of equal or greater value
  • Write about your find in the cache logbook
  • Log your experience online

Necessary items for geocaching

  • GPS device or GPS-enabled mobile phone
  • Online membership on a geocaching website


  • A logbook or logsheet for you to log your find.
  • An item that previous visitors may have left behind

Types of Caches

  • Micro: less than 100 mL
  • Small: 100 mL or larger, but smaller than 1 L
  • Regular: 1L or larger, but less than 20 L
  • Large: 20 L or larger


  • Promotes physical activity: Depending on the location of the geocache, people will need to traverse diverse terrains.
  • Promotes a feeling of self accomplishment: Builds self esteem in a person whenever they find a geocache, especially if it's well hidden.
  • Promotes education: Many geocaches are located in historical locations that contain information about the location. Additionally, some geocaches give well-known information, while others give arcane trivia that enriches the knowledge of those who find them


  • May not always be safe, depending on the location of a cache. Each geocaching website will give appropriate warnings for each of its hidden geocaches.
  • People need to take responsibility for their own safety and know their limits.

What platform does geocaching run on?

  • Any and all platforms, including Windows, Mac, and Linux.
  • Only limitations are the GPS devices and/or mobile phones with GPS capabilities.


  • Optional premium memberships online.
  • GPS device
  • Appropriate attire depending on location of geocache


Similar to geocaching, letterboxing is a treasure-hunting activity. A person hides a waterproof box somewhere, hides an object in it, and then writes directions to the box.4



Local tourism boards, the National Park Service, and historical associations.

See Also

Mirror Worlds