Geocaching is an outdoor recreational activity, a type of paper chase. The coordinates of the place, where the "cache" is hidden, can be found on the internet. The geocachers use a Global Positioning System (GPS) receiver or mobile device like Android-iPhone and other navigational techniques like compass to play "hide and seek" for buried or hidden containers called "geocaches" or "caches". These can be hidden anywhere in the world. A Geocache is a waterproof container, that contains a logbook to keep track of those who found the cache.
This hobby was founded by Dave Ulmer in 2000.
- The Complete Idiot's Guide to Geocaching by Jack W. Peters (ISBN 1-59257-235-9)
- Geocaching For Dummies by Joel McNamara (ISBN 978-0-7645-7571-6)
- The Joy of Geocaching by Paul and Dana Gillin (ISBN 1-88495-699-8)
- The Essential Guide to Geocaching by Mike Dyer (ISBN 1-55591-522-1)
- Geocaching: Hike and Seek with Your GPS by Erik Sherman (ISBN 978-1590591222)
- Let's Go Geocaching by DK Publishing (ISBN 978-0-7566-3717-0)
- The Geocaching Handbook (Falcon Guide) by Layne Cameron and Dave Ulmer (ISBN 978-076273044)
- Geocaching Video produced by Wisconsin Public Television