Hiking not exciting enough for you? Try Geocaching.
Geocaching is a sport in which you try to locate a specific destination using a GPS receiver. It's sort of a treasure hunt. You should start by creating a free account at the registration page of the Geocaching.com website.
The destination is known as a cache. The cache will be identified by clues and a longitude/latitude reference. There are varying degrees of difficulty in both terrain to cover and challenge of locating the cache. Normally, the clues are difficult to interpret, adding to the challenge.