Geocaching is a form of treasure hunt where you use a GPS enabled device, such as a smartphone, to try to locate a hidden cache. Caches can be hidden in urban areas or rural areas. The caches vary in size from large metal boxes to microcaches the size of the tip of your finger. Each cache contains a log book (yes, even the very small ones) which you sign when you find it. Larger caches contain "treasure" which you can take, if you leave an item of similar value in the cache. The treasure include items such as keyrings, toy figures etc. In addition to signing the logbook a log is submitted to the Geocaching website on the internet.

There are several different types of cache some are just hidden at the location, some require a puzzle to be solved to help you find the cache, others  may be multi caches where one cache contains a clue ot the location of the next. Caches are quite often disguised as common objects such as small logs, bolts in a fence, stones, bricks and even snails. There are 2,383,769 caches hidden worldwide,  so there is always one not too far away in a populated area.

Some caches contain trackables. A trackable has a unique number on it which is used to enable the finder to log where the trackable is found and where the finder sunsequently hides it in another cache. It is therefore possible to track the movement of a trackable from place to place. I have found trackables that have been all over the world and travelled many thousands of miles. Some trackables have an aim, such as to visit seaside places, canals etc.