Geocaching.com
Geocaching is a real-world, outdoor treasure hunting game. Players try to locate hidden containers, called geocaches, using GPS-enabled devices and then share their experiences online. The GPS coordinates for more than 1.7 million geocache listings around the world can be found on Geocaching.com. Geocaching.com also offers a Geocaching application for iPhone, Android, and Windows Phone 7 devices.
What is Geocaching?