"Geocaching is a high-tech treasure hunting game played throughout the world by adventure seekers equipped with GPS devices. The basic idea is to locate hidden containers, called geocaches, outdoors and then share your experiences online. Geocaching is enjoyed by people from all age groups, with a strong sense of community and support for the environment."
Last night my friend and I went out and found a few caches that are just 15min from where I live and I saw more things/places I never have. It is so cool that way. If you can, you need to try it.
A play by play of one of the caches we found: (sorry about the quality of the photos)