GPS scavenger hunt

Geocaching, also GPS scavenger hunt, is a kind of treasure hunt. The search is alternatively possible without a GPS receiver.

A scavenger hunt is usually a watertight container in which a logbook and often also various small items of exchange are located. The visitor can log in to document his successful search. Then the scavenger hunt is hid again at the point where it was previously found. The find can be noted on the Internet on the associated page and optionally supplemented by photos. So can other people – especially the hideaway or owner – to follow the events around the Scavenger hunt. It is essential in the entire search and exchange process that the project is not recognized by other persons present and thus remains hidden from the uninitiated persons of the scavenger hunt.


The Beginnings
Geocaching can be traced back to the much older letterboxing, which also hides containers in different places, which are usually searched for without GPS support. The search is based on clues and a compass. The container is each a special stamp, with which one notes the find in his personal stamp book. It has been proven that letterboxing already existed in Dartmoor in southern England in 1854 and it is still very popular there.

Since the 1980s, the Nuuksion Metsäsissit in the Helsinki area has also practiced scavenger hunts using only a map and 10 meter accuracy, hiding containers of various contents. Then they gave the determined coordinates to acquaintances, who could thus make the treasure hunt. From the 1990s, the GPS signal was used for the first time to improve the accuracy of the coordinates.

Beginning of the modern scavenger hunt
Only by switching off the artificial deterioration of accuracy (Selective Availability) of the GPS signal for civilian users by the US government on 2 May 2000 it has been increased from 100 meters to about 10 meters and in the use of GPS devices practicable in the private field. To celebrate this improvement, on May 3, 2000, Dave Ulmer proposed in the Usenet newsgroup sci.geo.satellite-nav, titled “The Great American GPS Stash Hunt,” to launch a worldwide game and container at special locations Hide exchange items and a logbook. As rules he formulated “Get some stuff, Leave some stuff” – “Take stuff out, leave stuff” and keep a logbook in which the finders can register and document the exchange of items.

The first scavenger hunt
On May 3, 2000, Ulmer buried a black plastic bucket near the city of Portland, Oregon, at 45 ° 17 ‘27.6 ” N, 122 ° 24’ 48″ W, where he next to CDs, a videocassette, a dollar bill, a book and a slingshot also deposited a tin with beans. He then published the coordinates of the hiding place in the newsgroup. Within a day after the release was Stash (English “secret place”, “secret camp”) as the first of Mike Teague found. Three days later, he created a private website where he found the growing number of stashes♁and documented their coordinates.

The original Stash by Ulmer was later heavily damaged and does not exist in its original form. To commemorate this were placed a new Scavenger hunt and a plaque at the same point 2,001th During the preparations for the cementing of the memorial plaque was found the old tin can on the spot, had lain as an object of exchange in the first Stash. Meanwhile, this is shown as a travel bug at geocaching events.

On May 30, 2000, the term geocaching was first proposed in a newsgroup to avoid negative connotations of the word stash. On September 2, 2000, Jeremy Irish announced in this newsgroup that he had created his own geocaching site at This took over all previous entries from the old page, which Mike Teague could not update because of time constraints.

Worldwide distribution
According to the database of what is now the largest scavenger hunt directory,, there are now more than 3 million active scavenger hunts worldwide. There is at least one hidden scavenger hunt in almost every state on earth. The only active off-planet is on the International Space Station (ISS).

In the US, there are more than 1 million most scavenger hunts (as of September 2017). There are over 367,000 in Germany, over 48,000 in Austria and over 31,000 scavenger hunts in Switzerland. The fewest scavenger hunts are in North Korea and Somalia, each with 0 pieces.

The largest scavenger hunt per capita penetration in January 2007 was in the Nordic countries of Sweden, Norway, Finland and Denmark.

The first scavenger hunt in Germany was hidden on 2 October 2000 by scavenger huntr Ferenc south of Berlin in Brandenburg. He was named First Germany and has now been archived. With more than 56,000 pieces, most scavenger hunts are currently in North Rhine-Westphalia. The largest scavenger hunt density is about 4.4 scavenger hunts / km² in Berlin and about 3.6 scavenger hunts / km² in Hamburg (as of September 2017). In absolute terms, Germany is the country with the highest geocaching number after the USA.

The first Austrian scavenger hunt was called Austria’s First. This too has now been archived; Today, a newly published scavenger hunt reminds him of the same coordinates. With more than 10,900 most scavenger hunts can be found in Lower Austria ; With more than 2,400 scavenger hunts, Vienna has the largest scavenger hunt density of approx. 5.8 scavenger hunts / km² in Austria (as of September 2017).

There are almost 31,000 scavenger hunts in Switzerland, most of them in the agglomeration areas of the Swiss Mittelland and in the urban area.

Traditional geocaching gave birth to GeoCaching – an active urban game of the Encounter project. The game is quite similar to geocaching but has time limitations and hints.

Scavenger hunts vary in size, difficulty, and location. Simple caches that are placed near a roadside are often called “drive-bys”, “park ‘n grabs” (PNGs), or “cache and dash”. Scavenger hunts may also be complex, involving lengthy searches, significant travel, or use of specialist equipment such as SCUBA diving, kayaking, or abseiling. Different geocaching websites list different variations per their own policies.

Container sizes range from “nanos”, particularly magnetic nanos, which can be smaller than the tip of a finger and have only enough room to store the log sheet, to 20-liter (5 gallon) buckets or even larger containers, such as entire trucks. The most common cache containers in rural areas are lunch-box-sized plastic storage containers or surplus military ammunition cans. Ammo cans are considered the gold standard of containers because they are very sturdy, waterproof, animal- and fire-resistant, relatively cheap, and have plenty of room for trade items. Smaller containers are more common in urban areas because they can be more easily hidden.

Caches can be grouped in three categories – with and without a paper log, and events.

The following types do not have paper logs.

Scavenger hunt types
A BIT Cache is a laminated card with a QR code, similar to Munzee. The BIT Cache also contains a URL and a password, for logging purposes. They are listed exclusively on

Virtual caches are coordinates for a location, which has some other described object. Validation for finding a virtual cache generally requires one to email the cache hider with information such as a date or a name on a plaque, or to post a picture of oneself at the site with GPS receiver in hand. New virtual caches are no longer allowed by Groundspeak, but they remain supported by other sites.

Earthcaches are virtual caches that are organized by the Geological Society of America. The cacher usually has to perform a task which teaches him/her an educational lesson about the earth science of the cache area.

Locationless/Reverse caches are 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 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.

Webcam caches are virtual caches whose coordinates have a public webcam. The finder is often required to capture their image from the webcam for verification of the find. New webcam caches are no longer allowed by Groundspeak, but they remain supported by other sites.

Finally, a USB Cache or Dead Drop cache location has a USB drive embedded (with permission) into walls or other structures. The cache is retrieved by connecting a device that has a USB port and that is able to read standard text files.

The following types have logs, at least at the final location.

A Multi-cache consists of multiple discoveries of one or more intermediate points containing the coordinates for the next stage; the final stage contains the log book. An Offset cache is a multi-cache in which 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.

A Night Cache is multi-stage and intended to be found at night by following a series of reflectors with a flashlight to the final cache location.

A Chirp Cache is a Garmin-created innovative advance on multi caches using new wireless beacon technology. The Chirp stores hints, multicache coordinates, counts visitors and confirms the cache is nearby. These caches were fully supported at, but they caused considerable discussion and some controversy at Groundspeak, where they were given a new “attribute”.

A Wherigo cache is a multi-stage cache hunt that uses a Wherigo “cartridge” to guide the player to find a physical cache sometime during cartridge play, usually at the end. Not all Wherigo cartridges incorporate scavenger hunts into game play. Wherigo caches are unique to the website.

Guest Book Caches use guest books often found in museums, tourist information centers, etc. They are listed exclusively at

A Letterbox Hybrid Cache is a combination of a scavenger hunt 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.

Moving/Travelling caches are found at a listed set of coordinates. The finder hides the cache in a different location, and updates the listing, essentially becomes the hider, and the next finder continues the cycle. This cache type is supported by multiple sites.

Mystery/puzzle caches require 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. Finally, Challenge Caches, (a subtype of the Mystery cache) require a scavenger huntr to complete a reasonably attainable geocaching-related task before being able to log the find. Examples include finding a number of caches that meet a category, completing a number of cache finds within a period of time, or finding a cache for every calendar day, etc.

There are a few kinds of events.

An Event Cache is a gathering organized and attended by scavenger huntrs.

Cache-In Trash-Out (CITO) Events are coordinated activities of trash pickup and other maintenance tasks (such as constructing footpaths, planting trees and removing invasive species) to improve the environment. CITO is an ongoing environmental initiative created by Groundspeak Inc. related to geocaching which encourages scavenger huntrs to clean up parks and other areas. This is done in two ways: specific events, traditionally around the time of Earth Day each year, in which groups go around picking up litter and maintaining the landscape while finding scavenger hunts.

A Mega Event is defined by attendance of over 500 people. Mega Events are typically annual events, usually attracting scavenger huntrs from all over the world.

A Giga Event is an event with an attendance of over 5000 people, also attracting scavenger huntrs from worldwide.

Finally, a GPS Adventures Maze Exhibit is an exhibit at various museums and science centers in which participants in the maze learn about geocaching. These “events” have their own cache type on and include many non-scavenger huntrs.

Geodashing is an outdoor sport in which teams of players use GPS receivers to find and visit randomly selected “dashpoints” (also called “waypoints”) around the world and report what they find. The objective is to visit as many dashpoints as possible.

Unlike geocaching, nothing is to be left at the dashpoints; the sole objective is to visit them within the time limit.

The first game, organized by, ran for two months (June and July 2001); each subsequent game has run for one month. Players are often encouraged to take pictures at the dashpoints and upload them to the site.

Geocaching from space is a combination of flight to near space, the geocaching game, and a unique science experiment. The first Stratocaching event was held on 16 November 2013 in Prague and was successful. Ten caches and two “radioseeds” went up to 30 km (19 mi) into the stratosphere on a gondola called Dropion module carried by a high-altitude balloon. The caches and seeds then fell to earth for people to find.


Obtaining data
GPX files containing information such as a cache description and information about recent visitors to the cache are available from various listing sites. Scavenger huntrs may upload scavenger hunt data (also known as waypoints) from various websites in various formats, most commonly in file-type GPX, which uses XML. Some websites allow scavenger huntrs 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. In recent years, Android and iPhone users have been able to download apps such as GeoBeagle that allow them to use their 3G and GPS-enabled devices to actively search for and download new caches.

Converting and filtering data
A variety of geocaching applications are available for scavenger hunt data management, file-type 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 means hunting a scavenger hunt without a physical printout of the cache description. Traditionally, this means that the seeker has an electronic means of viewing the cache information in the field, such as pre-downloading the information to a PDA or other electronic device. Various applications are able to directly upload and read GPX files without further conversion. Newer GPS devices released by Garmin, DeLorme and Magellan have the ability to read GPX files directly, thus eliminating the need for a PDA. Other methods include viewing real-time information on a portable computer with internet access or with a Internet-enabled smart phone. The latest advancement of this practice involves installing dedicated applications on a smart phone with a built-in GPS receiver. Seekers can search for and download caches in their immediate vicinity directly to the application and use the on-board GPS receiver to find the cache.

A more controversial version of paperless caching involves mass-downloading only the coordinates and cache names (or waypoint IDs) for hundreds of caches into older receivers. This is a common practice of some cachers and has been used successfully for years. In many cases, however, the cache description and hint are never read by the seeker before hunting the cache. This means they are unaware of potential restrictions such as limited hunt times, park open/close times, off-limit areas, and suggested parking locations.


Mobile devices
The website now sells mobile applications which allow users to view caches through a variety of different devices. Currently, the Android, iPhone, and Windows Phone mobile platforms have applications in their respective stores. The apps also allow for a trial version with limited functionality.

Additionally “c:geo – opensource” is a free opensource full function application for Android phones that is very popular. This app includes similar features to the official Geocaching mobile application, such as: View caches on a live map (Google Maps or OpenStreet Maps), navigation using a compass, map, or other applications, logging finds online and offline, etc.

Geocaching enthusiasts have also made their own hand-held GPS devices using a Lego Mindstorms NXT GPS sensor.

GPS receiver
To find scavenger hunts you need a device with a GPS receiver. The use of topographic maps can facilitate orientation in the field, while road maps and routing functions facilitate the journey to the destination area.

In addition to GPS handsets, notebooks, PDAs, mobile navigation systems and smartphones with integrated or external GPS receivers are alternatively suitable for geocaching purposes. However, they are less geared to the needs of demanding scavenger hunts than GPS devices that have long battery life and are protected against shock and rain.

In open terrain or on the water GPS devices can determine the position very precisely. In dense forest, in canyons, or between urban facades in cities, older GPS devices in particular have difficulty finding their position with sufficient accuracy. However, the further development of the devices constantly improves the reception under difficult conditions.

Different software solutions facilitate the pursuit of the hobby, but are not a requirement. This allows scavenger hunts and their listings to be better managed, filtered by various criteria, and stored on portable systems such as PDAs or smartphones. As a result, it is not necessary to print the listings (keyword: “paperless geocaching”).


Scavenger huntbehälter with attached camouflage net
Scavenger hunts are usually hidden and camouflaged so that they are not found or recognized by uninvolved persons. In addition, the principle is to keep scavenger hunt hiding as secret as possible and to go unobserved. Otherwise, there is a risk that the scavenger hunt will be damaged or lost by third parties.

Outsiders who are not players be as “Muggles” (English muggles called). The term comes from the Harry Potter books, where “Muggle” is used as a term for “people without magical abilities”.

Scavenger hunt listing websites have their own guidelines for acceptable scavenger hunt publications. Government agencies and others responsible for public use of land often publish guidelines for geocaching, and a “Scavenger huntr’s Creed” posted on the Internet asks participants to “avoid causing disruptions or public alarm”. Generally accepted rules are to not endanger others, to minimize the impact on nature, to respect private property, and to avoid public alarm.

The reception from authorities and the general public outside scavenger hunt participants has been mixed to hostile.

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 scavenger hunt, such as the evacuation of a busy street in Wetherby, Yorkshire, England in 2011.

Schools have also been evacuated when a cache has been seen by teachers or police, such as the case of Fairview High School in Boulder, Colorado in 2009. A number of caches have been destroyed by bomb squads. Diverse locations, from rural cemeteries to Disneyland, have been locked down as a result of such scares.

The placement of scavenger hunts has occasional critics among some government personnel and the public at large who consider it littering. Some scavenger huntrs act to mitigate this perception by picking up litter while they search for scavenger hunts, a practice referred to in the community as “Cache In Trash Out”. Events and caches are often organized revolving around this practice, with many areas seeing significant cleanup that would otherwise not take place, or would instead require federal, state or local funds to accomplish. Scavenger huntrs are also encouraged to clean up after themselves by retrieving old containers once a cache has been removed from play.

Geocaching is legal in every country except North Korea (where GPS and all other mobile devices are illegal to possess) and is usually positively received when explained to law enforcement officials. However, certain types of placements can be problematic. Although generally disallowed, hiders could place caches on private property without adequate permission (intentionally or otherwise), which encourages cache finders to trespass. Caches might also be hidden in places where the act of searching can make a finder look suspicious (e.g. near schools, children’s playgrounds, banks, courthouses, or in residential neighborhoods), or where the container placement could be mistaken for a drug stash or a bomb (especially in urban settings, under bridges, near banks, courthouses, or embassies). As a result, scavenger huntrs are strongly advised to label their scavenger hunts where possible, so that they are not mistaken for a harmful object if discovered by non-scavenger huntrs.

As well as concerns about littering and bomb threats, some scavenger huntrs hide their caches in inappropriate locations, such as electrical boxes, that may encourage risky behaviour, especially amongst children. Hides in these areas are discouraged, and cache listing websites enforce guidelines that disallow certain types of placements. However, as cache reviewers typically cannot see exactly where and how every particular cache is hidden, problematic hides can slip through. Ultimately it is also up to cache finders to use discretion when attempting to search for a cache, and report any problems.

Regional rules for placement of caches have become quite complex. For example, in Virginia, the Virginia Department of Transportation and the Wildlife Management Agency now forbids the placement of scavenger hunts on all land controlled by those agencies. Some cities, towns and recreation areas allow scavenger hunts with few or no restrictions, but others require compliance with lengthy permitting procedures.

The South Carolina House of Representatives passed Bill 3777 in 2005, stating, “It is unlawful for a person to engage in the activity of geocaching or letterboxing in a cemetery or in an historic or archeological site or property publicly identified by an historical marker without the express written consent of the owner or entity which oversees that cemetery site or property.” The bill was referred to committee on first reading in the Senate and has been there ever since.

Source from Wikipedia