I'd have to say paintball; woodsball or scenarioball to be specific. I'm addicted to woodsball. Just like the name suggests, you go out into the woods and play paintball. We've combined woodsball and geocaching to an extent before. We will normally split into two teams and spend about 3-4 days in the woods behind my house. It's a good 4 or 5 square miles back there. Then, using radios, we'll put each team's coordinates for their base or fort into our gps's, as well as other objectives we want to accomplish. One of the ones we normally do is capture the flag. It is very neat to use the gps because you are such a far way apart. If you have the time and resources, you should try it!