Whether you're looking for a fun family activity, or a new outdoor singles scene, you might check out Geocaching. Geocaching is a trendy new adventure game for GPS users. Participating in a cache hunt is a good way to take advantage of the full capability of a GPS unit(if you don't have GPS, stay tuned). 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. If you take something out, you should try to leave something for the cache. What is usually in a cache? A cache can come in many forms but the key item will invariably be the logbook. The logbook contains information from the founder of the cache and notes from the cache's visitors. A logbook might contain information about nearby attractions, coordinates to other unpublished caches, and even jokes written by visitors. If you get some information from a logbook you should give some back. At the very least you can leave the date and time you visited the cache. Larger caches may consist of a waterproof plastic bucket placed tastefully within the local terrain. The bucket might contain any number of more or less valuable items. These items turn the cache into a true treasure hunt. Geocaching is really just the next evolution of the centuries old tradition of letterboxing with trails that can be found all over New Jersey -- even as close as Bloomfield & Montclair.
from EcoRealty
This has been one of my favourite hobbies for some time.