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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 value. Today, well over 800,000 geocaches are registered on various websites devoted to the pastime. Geocaches are currently placed in over 100 countries around the world and on all seven continents, including Antarctica.


Geocaching is similar to the 150-year-old letterboxing, which uses references to landmarks and clues embedded in stories. However, geocaching was imagined shortly after the removal of Selective Availability from GPS on May 1, 2000 because the improved accuracy of the system allowed for a small container to be specifically placed and located. The first documented placement of a GPS-located cache took place on May 3, 2000, by Dave Ulmer of Beavercreek, Oregon. The location was posted on the Usenet newsgroup [news://sci.geo.satellite-nav sci.geo.satellite-nav] . By May 6, 2000, it had been found twice and logged once (by Mike Teague of Vancouver, Washington). According to Dave Ulmer's message, the original stash was a black plastic bucket buried most of the way in the ground and contained software, videos, books, food, money, and a slingshot.

Origin of the name

The activity was originally referred to as GPS stash hunt or gpsstashing. This was changed after a discussion in the gpsstash discussion group at eGroups (now Yahoo!). On May 30, 2000, Matt Stum suggested that "stash" could have negative connotations, and suggested instead "geocaching.


For the traditional geocache, a geocacher will place a waterproof container, containing a log book (with pen or pencil) and trinkets or some sort of treasures, then note the cache's coordinates. These coordinates, along with other details of the location, are posted on a website. Other geocachers obtain the coordinates from the Internet and seek out the cache using their GPS handheld receivers. The finding geocachers record their exploits in the logbook and online. Geocachers are free to take objects from the cache in exchange for leaving something of similar or higher value, so there is treasure for the next person to find.

Typical cache treasures are not high in monetary value but may hold personal value to the finder. Aside from the logbook, common cache contents are unusual coins or currency, small toys, ornamental buttons, CDs, or books. Also common are objects that are moved from cache to cache, such as Travel Bugs or Geocoins, whose travels may be logged and followed online. Occasionally, higher value items are included in geocaches, normally reserved for the "first finder", or in locations which are harder to reach.

Geocache container sizes range from film canisters often called "microcaches," too small to hold anything more than a tiny paper log, to five-gallon buckets or even larger containers.

If a geocache has been vandalized or stolen, it is said to have been "muggled" or "plundered." The former term plays off the fact that those not familiar with geocaching are called "geo-muggles" or just muggles, a term popularised by the Harry Potter series of books.

If a cacher discovers that a cache has been muggled, it can be logged as needing maintenance, which sends an e-mail to the cache owner so it can be repaired, replaced, or archived (deactivated).

Caches usually cannot be seen easily. Some are the same color as the object that they are hidden in or on.


Geocaches vary in size, difficulty, and location. Simple caches are often called "drive-bys," "park 'n' grabs" ("PNGs"), or "cache and dash." Geocaches may also be complex, involving lengthy searches or significant travel. Examples include staged multi-caches; underwater caches, 50 feet (15 m) up a tree, after long offroad drives, on high mountain peaks, on the Antarctic continent, and above the Arctic Circle. Different geocaching websites list different variations per their own policies (e.g. does not list new Webcam, Virtual, Locationless, or Moving geocaches).

Variations of geocaches include:

  • Traditional: The basic cache type, a traditional cache must include a log book of some sort, but may include trade or trackable items. A traditional cache is distinguished from other cache variations in that the geocache is found at the coordinates given and involves only one stage.
  • Event Cache: This is a gathering organized and attended by geocachers. Physical caches placed at events are often active only for the event date.
    • Cache-In Trash-Out (CITO) Events: This variation on event caching is a coordinated activity of trash pickup and other maintenance to improve the environment.
  • Letterbox Hybrid: A letterbox hybrid cache is a combination of a geocache and a letterbox in the same container. A letterbox has a rubber stamp and a logbook instead of tradable items. Letterboxers carry their own stamp with them, to stamp the letterbox's log book and inversely stamp their personal log book with the letterbox stamp. The hybrid cache contains the important materials for this and may or may not include trade items. Whether the letterbox hybrid contains trade items is up to the owner.
  • Locationless/Reverse: This variation is similar to a scavenger hunt. A description is given for something to find, such as a one-room schoolhouse, and the finder locates an example of this object. The finder records the location using their GPS handheld receiver and often takes a picture at the location showing the named object and his or her GPS receiver. Typically others are not allowed to log that same location as a find. (This is now part of Waymarking.)
  • Moving/Traveling: Similar to a traditional geocache, this variation is found at a listed set of coordinates. The finder uses the log book, trades trinkets, and then hides the cache in a different location. By updating this new location on the listing, the finder essentially becomes the hider, and the next finder continues the cycle.
  • Multi-cache: This variation consists of multiple discoveries of one or more intermediate points containing the coordinates for the next stage; the final stage contains the log book and trade items.
    • Offset: This cache is similar to the multi-cache except that the initial coordinates are for a location containing information that encodes the final cache coordinates. An example would be to direct the finder to a plaque where the digits of a date on the plaque correspond to coordinates of the final cache.
    • Night Cache: These multi-stage caches are designed to be found at night and generally involve following a series of reflectors with a flashlight to the final cache location.
  • Mystery/puzzle: This cache requires one to discover information or solve a puzzle to find the cache. Some mystery caches provide a false set of coordinates with a puzzle that must be solved to determine the final cache location. In other cases, the given location is accurate, but the name of the location or other features are themselves a puzzle leading to the final cache. Alternatively, additional information is necessary to complete the find, such as a padlock combination to access the cache.
  • Virtual: Caches of this nature are coordinates for a location that does not contain the traditional box, log book, or trade items. Instead, the location contains some other described object. Validation for finding a virtual cache generally requires you to email the cache hider with information such as a date or a name on a plaque, or to post a picture of yourself at the site with GPS receiver in hand.
  • Earthcache: Organized and maintained by the Geological Society of America, the EarthCache program is a subset of geocaching in which the "treasure" a cacher finds is an educational lesson rather than a physical container. An Earthcache's essential element is educational information about the earth science of the cache area and an interactive educational task directly engaging the cacher in that geology. EarthCaches are submitted at and transferred to during the review process. EarthCache program sponsors include Groundspeak, National Geographic, Subaru, and the National Park Service.
  • Webcam: Similar to a virtual cache; there is no container, log book, or trade items for this cache type. Instead, the coordinates are for a location with a public webcam. Instead of signing a log book, the finder is often required to capture their image from the webcam for verification of the find.
  • Wherigo cache: A Wherigo cache is similar to a multi-stage cache hunt that uses a Wherigo cartridge to guide the player. The player plays the cartridge and finds a physical cache sometime during cartridge play, usually at the end. Wherigo cartridges are found on their own website, Not all Wherigo cartridges incorporate geocaches into game play.

Obtaining data

GPX files contain information such as a cache description and information about recent visitors to the cache. Geocachers may upload geocache data (also known as waypoints) from various websites in various formats, most commonly in filetype GPX, which uses XML. Some websites allow geocachers to search (build queries) for multiple caches within a geographic area based on criteria such as Zip Code or coordinates, downloading the results as an email attachment on a schedule. Although often a time-consuming process with many possibilities for error, appropriate client software allows cachers to build individual GPX files.

Converting and filtering data

A variety of geocaching applications are available for geocache data management, filetype translation, and personalization. Geocaching software can assign special icons or search (filter) for caches based on certain criteria (e.g. distance from an assigned point, difficulty, date last found).

Paperless geocaching employs PDAs or other electronic devices to carry geocache information instead of paper. Various applications are able to directly upload and read GPX files without further conversion.


When geocaching in busy locations, searching for a cache can require tact and craftiness to avoid the attention of the general public. The person hiding a geocache frequently takes this into account so that searchers will not cause undue alarm. Cachers have been approached by police and questioned when they were seen as acting suspiciously. Other times, investigation of a cache location after suspicious activity was reported has resulted in police and bomb squad discovery of the geocache. A number of caches have been destroyed by bomb squads.

Individual geocaching websites have developed their own guidelines for acceptable geocache publications. Though not universally required, the Geocacher's Creed provides ethical search guidelines. Government agencies and others responsible for public use of land often establish their own guidelines for geocaching.


Numerous websites list geocaches around the world.

The first and currently the largest is, owned by Groundspeak, Inc., which began operating in 2000. With a worldwide membership, lists hundreds of thousands of caches. As of August 2008 over 641,175 caches had been hidden with more created daily. Each cache is reviewed by regional cache reviewers before publication with an emphasis on family-oriented caching. Free basic membership allows users to see coordinates for most caches in its database; premium membership includes a fee for additional features, including advanced search tools and caches designed for premium members. no longer lists new caches without a physical container, including locationless/reverse and webcam; however, older caches of these types have been grandfathered in (except for locationless/reverse, which are completely archived). Earthcaches are the exception to the no-container rule; they are caches in which players must answer geological questions to complete the cache. Groundspeak created a waymarking website to handle all other non-physical caches.

Geocaching also supports the discovery of benchmarks, which are a location "known to a high degree of accuracy Sometimes these can be metal disks, radio towers, or a bolt in central locations or on a highway. Their main purpose is for surveying an area. Geocaching gives the longitude and latitude to this location and the user must rely on giving clues to find the benchmark. Some of these haven't been found for hundreds of years.

Geocaching With Navicache

Started as a regional listing service around February 2001, quickly gained popularity among those looking for a less restrictive alternatives to what was currently available. While many of's listings have been posted to other sites, they also offer many unique listings. also lists nearly any type of geocache (within reason) and does not charge to access any of the caches listed in their database. While all submissions are reviewed and approved, Navicache is more liberal in approving caches believing that the pastime belongs to participants rather than a governing agency.


Terracaching seeks to provide high-quality caches made so by the difficulty of the hide or from the quality of the location. Membership is managed through a sponsorship system, and each cache is under continual peer review from other members. embraces virtual caches alongside traditional/multi-stage caches and includes many locationless caches among the thousands of caches in its database.

In the United States, where most geocaching services are hosted, only a cache's coordinates are in public domain. Other cache information, including the description, is protected by copyright law. Geocaching websites vary in active protection of cache data.

See also

Further reading

  • The Essential Guide to Geocaching by Mike Dyer (ISBN 1-55591-522-1)
  • The Complete Idiot's Guide to Geocaching by Jack W. Peters (ISBN 1-59257-235-9)
  • Geocaching For Dummies by Joel McNamara (ISBN 978-0764575716)
  • Geocaching: Hike and Seek with Your GPS by Erik Sherman (ISBN 978-1590591222)
  • The Geocaching Handbook (Falcon Guide) by Layne Cameron and Dave Ulmer (ISBN 978-076273044)
  • Let's Go Geocaching by DK Publishing (ISBN 978-0756637170)
  • It's a Treasure Hunt! Geocaching & Letterboxing by Cq Products (ISBN 978-1563832680)
  • Open Your Heart with Geocaching: Mastering Life Through Love of Exploration by Jeannette Cezanne (ISBN 978-1601660046)


External links

Geocache listing sites

Geocaching Guides

Policy information

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