Even if you have never heard of Geocaching, you’ll find the following network link an interesting way to explore the Earth. What is Geocaching? It’s a recreational byproduct of the GPS and the Internet. From the Geocaching FAQ:
The basic idea is to have individuals and organizations set up caches all over the world and share the locations of these caches on the internet. GPS users can then use the location coordinates to find the caches. Once found, a cache may provide the visitor with a wide variety of rewards. All the visitor is asked to do is if they get something they should try to leave something for the cache.