This 'game' you could call it is everywhere, even in many other countries! In some states it is bigger than others, it origintad in Washington, so here on the West side of the country it is really big, but I know there are many in every state. Go to
www.geocaching.com. Our team name is AZBliss02. It is convenient to have a GPS, but we found quite a few w/o one. It is great because you get outside, sometimes hiking, going to great parks all over the city, and you get to treasure hunt! Plus it is such good excersise and excitement for your little doggie (or big). There are some also called 'urban' caches where they are located say, under a light fixture in a parking lot at your local grocery or something. Isn't it strange to think someone hid something there and you don't even know it? Those are mosytly 'micro cahces', what some of you others were explaining, there are no trades items just a log, whenever you find a cache you sign the log book saying you found it. And you have to be sneaky when you are out looking for these, you don't want other people around to see what you are doing and find the cache also. I must say when my boyfriend first told me about this I was kinda not interested, but after going out our first time it was a lot of fun! It is such a good thing for families, especially those with kids, and also retired ones love this game!