>>Geocaching is pretty common and I can't tell how many boxes I've found while herping. those hippies like to hide thier boxes in prime snake habitat I tell you lol.
Well, I can tell you that geocaching is far from a "hippie" sport although i'm sure there are some hippies doing it. 
Actually, there are people for ALL walks of life geocaching. You'd be surprised at the number of retired people involved in it.
My family and I have been geocaching since Sept. of 02. I was out herping in Springfield, Mo. with one of the guys who is working on updating the Field Guide To Reptiles and Amphibians of Missouri and found a cache hidden under a rock ledge. It was a rubber maid container so my first thought was that another herper had been there before us and had stashed a snake there for pickup later.
When I opened it, it was full of toys and a log book.
I had no idea what it was but the other guy was familiar with caching and filled me in on it. Since I had just bought my 1st gps I saw gecaching as a great way to learn how to use my receiver.
Basically, you hide the container or "cache" (without harming the environment) which can be as large as an ammo can or as small as your fingernail. You then fill out the cache page at www.geocaching.com with information about the cache and the coordinates and people around the world (over 200 countries) can then look for it.
Each cache has 2 difficulty ratings. One is the overall difficulty and the other is the terrain. Both are rated 1 to 5 with 5 being the most difficult.
Most caches contain only inexpensive toys or trinkets for the kids, but sometimes there are valuable items such as old coins inside. If you take something you're supposed to leave something or equal or greater value.
Try it, you'll like it!
Eric
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