Even easier because you don't need gps though with today's smart phones that isn't hard to do anymore, is letter boxing. Same basic idea, but there you sign the log book and perhaps leave a goody. Websites generally have the clues.
Another one, started recently is "rocks", painted rocks are placed around town with date and site on them and you exchange one of yours for the one that you find. I know lots of folks doing this one in oregon. Again, there are websites with the clues.
Letter boxing and the rocks are like a treasure hunt and you follow clues. Geochacheing, you have GPS coordinates.
My girls do these things with their kids. They look up clues for new towns and areas before visiting and making finding the things part of getting to know a tourist area. Most of these have european and international followers as well, just use internet to find clues.
Geochacheing extends to the forests and woods in the Pacific Northwest so is really good if you like getting off the beaten path.