I'd just like to say that my partner and I have been keen geocachers for a few years and it's always a great thrill to find one of these hidden treasures. We love to follow a themed hunt, where there are a series of micro-caches laid by one person in a local area that sometimes have a little story linking them together.
We have a bumbag containing a geocaching kit, which includes a compass, a notepad, some tweezers, wet-wipes, a pencil and a small token to leave in the cache to say we have found it. We never swap or take anything. And we always log our find on the geocachers website and thank the person who planted the cache.
Not even attempted to do any geocaching in the buff as the rules state that a cache must always be left in a publicly accessible location - and we don't want to give anyone a heart attack!