Last weekend my brother and me went Geocaching.......we have been Geocaching for probably about 5+ years now.....we both have the exact same GPS.....all you do is plug the coordinates into the GPS and fallow the GPS to the cache..then once you find it you can take something from the container but you have to leave something in it's place and sign the log book or you can leave and take nothing and just sign the log book.....kinda like a scavenger hunt.....it's fun for hikers and just being out haveing a good time with bro.
Here is a link to the site to better understand how it all works
http://www.geocaching.com/