Well, in a nutshell, it's outdoor treasure-hunting using any GPS-enabled device!.
The caches themselves come in all different sizes, from lunchbox or ammunition box sized down to micro and nano caches. A micro is the size of a matchbox or film canister, whereas a nano is the size of a button battery. At the very least, a cache contains a log book or log sheet. There are all kinds of clever caches. Some are disguised as everyday objects such as a rock, bottle cap or even tuft of grass!
Larger caches contain a log book, pencil and assorted small, low value items and often nick-nacks for children. It is customary to exchange items of similar value.
The locations of'caches can vary from the local park or way out in the sticks at the end of a long trek.
Firstly the 'Geocachers' use the GPS to hide a cache at precise coordinates. They then upload the details, description and a clue to Geocaching.com
In order to find a cache, register for free at Geocaching.com and get started by searching your chosen area, either by postcode or town. Each cache page has details of the container, terrain, difficulty and an encripted clue. Choose your caches and download the details to your GPS.
Geocaches can be found worldwide and there are over 50 caches on or near the Tarka Trail alone. So get out and get hunting, you know you want to!