According to www.Geocaching.com:
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.
As of my writing this, there are 1,081,885 active geocaches in the world. Certainly with that many, there are some of these treasures near you.
This is one of the adventures that does cost a little bit of money, unless you already have a GPS receiver. You can use a good map, but a GPSr will be so much easier.
Once you have a GPSr, you just have to go to www.geocaching.com and register for a free account, search for caches in your area, load them into your GPSr, and go ‘caching!
Alone or With Friends
I started geocaching with my wife (then girlfriend) after receiving a GPSr for Christmas. The more caches we found, the more interested we became. It wasn’t long until we became curious about the names we were reading: Geo.Joe, B&TLand, theMusician, thePhotographer. We met with B&TLand and quickly discovered that we had new friends. They pointed us to a local group, the River Valley GeoCachers where we met others who shared our interests and with whom we enjoyed a number of outings.
The real treasure of this hobby is not the history that you will learn, the places that you will visit, or even the caches that you will find. It is the people that you will get to meet, and learn to call friends.
So get out there, and seek your treasure!