Geocaching is an outdoor recreational activity in which participants use a Global Positioning System receiver or mobile device to locate containers, known as "geocaches," at locations identified by coordinates all over the world (video below).
It is based on a much older hobby known as “letterboxing,” which is believed to have started in England 150 years ago, notes Time Magazine.
According to Devon Perspectives, that’s when James Perrott of Dartmoor put his calling card in a bottle where others would find it, which could then be exchanged for their own calling card, along with a log book for signing in and documenting the discovery. Soon, the letterboxing phenomenon spread across England and, more than a century later, caught on in the United States after a feature story in Smithsonian Magazine.
Since that time, an estimated 9,000 such letterboxes have been placed in public areas around the country.
When the U.S. government’s GPS technology became available to the public in 2000, it was used to develop a variation on letterboxing known as geocaching.
Credit for the development of geocaching is attributed to one Dave Ulmer, according to Geocaching.org, who hid a bucket of trinkets in the woods outside Portland, Oregon, and announced its location on an internet news group.
In that announcement, the hobby’s rules were defined, which include leaving a container enclosed with certain items which can be taken and replaced with other items, and a log book participants are encouraged to sign and date.