Q: What do geeks do when they want to spend time away from their keyboards?

A: They take their smart phone or GPS receiver and go geocaching.

What does the above have to do with open source? Do you use tools like c:geo? Then, you are using open source to go geocaching! Geocaching is an offline scavenger hunt, out in the real world, with the help of GPS coordinates. The person who hides the "cache" is the owner and prepares it by finding a nice hiding spot and putting sheet of paper, the log book into a cache container. Cache containers come in different kinds sizes and forms. The most popular kind is a 35mm film container. There are others that look like old rusty screws, parts of a tree, bird houses, or look-a-like rocks. The owner then hides the container, records its GPS coordinates, and makes it available to other geocachers so that they can go find the cache and sign the log book to record the finding.

There are a few sites on the Internet that serve as repositories for such caches, Geocaching.com probably being the most prominent. Geocachers can go there, search for caches in certain areas, and download the coordinates into their GPS device. In fact you don't need to have a GPS device, but can often print the description page and use a map. These sites also allow you to record your experience, which I talk about more below.

While originally there was only simply "go to these coordinates" caches (called traditional caches), many new types have been added, oriented towards mysteries that involve solving riddles to get the final coordinates, multi-caches that involve going to multiple stages in order to find the cache container, and event caches, where geocachers meet and talk about their favorite hobby.

The geocaching experience starts with the owner who identifies a nice spot to place a cache or a trail to follow through. There are times where a cache is carelessly placed, but very often they bring you to places or landmarks or pieces of art that you would have normally not passed by. A new experience. A good owner definitively shares his or her passion for this hobby. From time to time this passion is also reflected in hand-crafted containers or places that host the containers (e.g. this Geocache of the Week). When a cacher finds a cache she usually does not only sign the log book, but also records the findings at the aforementioned repositories like Geocaching.com or Opencaching.com. Many cachers write a few words about the place and their experience about getting there. Often photos are attached as well (there is a multi-cache leading from Munich to Venice as an awesome example).

If a cache cannot be found, many users log a DNF which means "did not find." A DNF can give a hint to the owner that the container has gone missing or that an additional hint in the cache description may be needed. Similar to if a cache is in bad condition (container broken, log book full or wet, etc.), users can log a "needs maintenance" to inform the owner to fix the cache.

Event caches do not involve a physical container, but are often regular meetings where cachers assemble to have fun together and talk about caching. At these events, information about new and cool caches are shared, additional hints exchanged, or even coordinates to where multiple cachers sit together and try to solve the riddles of mystery caches.

I am reminded of the open process in open source software, where someone starts by writing some code and publishing it. Others take and use it, blog about their findings, write bug reports, and so on. The original creator then incorporates the feedback and improves the experience for the users. Also, with community comes community meetups and from time to time a hackfest. Like the number of projects on GitHub and other hosting services is growing, the number of hidden geocaches is steadily growing. On Geocaching.com alone, there have been 1 million caches published in the United States alone, and a total of more than 2.4 million around the globe.

Geocaching is also family-friendly. Kids can hide and find caches the same way adults do. They may not yet be able to solve (complex) riddles, but in my experience, out in the field they often spot containers faster than adults! And non-cachers, or muggles, pay a lot less attention to kids than adults crawling under a bench to retrieve a container.