http://www.geocaching.com/ and type in your address or zip code to find out how many are around you. It's quite amazing.
At first I just mapped the coordinates and wrote down a description of where the geocaches are located, but my daughter and I quickly found out that geocaching is nearly impossible in our area without the use of a GPS device. There are these "greenbelts" (really dirt alleys) between houses in our neighborhood that lead to huge lots (like 20 acres) filled with sagebrush and trash. We weren't having any luck finding the geocaches based upon an icon on a map, so we drove back home and grabbed both my son and my son's GPS device.
The second geocache was a little more difficult to find. We had to move a row of tumbleweeds against a fence and dig around. I don't know what made me notice it, but there was a magnetic tin attached to a metal fence. Unfortunately, the logbook was soaking wet, so I wasn't able to sign it.
The third one was on a road that was flooded...
Here the kids are telling me to hurry up while we were searching for the fifth one...
By the time we stopped to look for the sixth one, my son was complaining that he wanted to go home, so we had to hurry. This one was planted on the border of the planter's property. We turned over every rock and looked under the one tree, but couldn't find it. When we got home I read the comments from those who found it, and realized that I should have paid attention to the title of the geocache, because I had the container in my hot little hand and didn't even realize it! Needless to say, we'll be making a return trip the next time I can convince the kids to go with me.
So far the biggest difference I see between geocaching and letterboxing is that I've never found a letterbox in a location that made me feel uncomfortable, while some of these geocaches were in very inappropriate locations. For instance, one was located on a lot overlooking a main road, right on a blind curve where people are supposed to be driving 25 MPH, but instead drive 45 MPH. Anyway, my daughter commented that no one was watching the road. All the drivers were gawking at us. Next thing we knew, we heard the sound of tires squealing and someone leaning on a horn. There was a near miss in which one driver nearly rear-ended another, so we quickly left without further searching for that geocache.
Also, many geocaches were planted in residential neighborhoods, and as soon as I parked my car, people started coming out of their houses to watch us, which makes me think that the people who planted the geocache did not bother to ask permission from the residents, and the residents are probably trying to figure out why strangers keep driving into their neighborhood, parking, and wandering around.
I like my privacy, so I can totally relate if neighbors are annoyed by all of the activity. Also, many of the geocaches were in locations near private backyards and our presence created a stir among the neighborhood dogs. I think in the future I will just stick to those located along trails or in business districts.
In the end we found four geocaches, didn't find two with the GPS device, and didn't find four without the GPS device. So, I made ten stops, all within ten miles of my home. I think the nearest letterbox to my home that I didn't plant is a twenty-minute drive, so it was nice to not have to burn so much gas geocaching.