Beyond PAC Hobby


by Bernhard Baumgartner, b2 electronics, Austria

“I use multi-million-dollar satellites to find Tupperware in the woods. What’s your Hobby?”  This is a sentence that could be read on T-shirts of Geocachers when Geocaching became a popular sport in the beginning of the 21st century.

In case you are a Geocacher yourself or if you want to learn more about this fantastic hobby feel free to contact me (Baumi_B) on:

At that time, Geocachers were equipped with professional handheld GPS receivers, which sometimes not even had the functionality to display maps. Things have drastically changed since these early days. Nowadays every smartphone is equipped with a GPS receiver and the use of GPS data has become a commodity.

Geocaching? You might ask yourself – haven’t I read something about this in the PAC world magazine already? – Well, you are right. In the Winter issue 2009 an article was published in this magazine. It was in the summer of 2023 when my wife Margit and I had the pleasure to meet up with Alex Apostolov in Santa Monica at Barney’s Beanery. Margit and I were at that time on our “Around the world in 85 days” trip and so Alex was contemplating if this trip could be something for a hobbyist article in PAC world. But then I made a strategical mistake and mentioned that Margit’s and my hobby Geocaching has played an important role planning our trip. And so, I am sitting here at my desk on a Sunday morning close to the deadline writing an article about a hobby that has been keeping us excited for over 15 years now. 

So, what is Geocaching?  If someone asks me my usual reply is: “Geocaching is Pokemon GO for grown-ups.” In general, it’s a GPS-supported treasure hunt to find boxes of different sizes and shapes hidden around the world. The boxes can be very small like the boxes for lighter flintstones (so called Nanocaches,) as huge as ammunition boxes or even bigger. In Austria there is a small cabin that is a walk-in Geocache (GC3V52D).  

At the time this article was written a total of 3,341,625 active Geocaches were available in 196 countries worldwide. All these Caches have been hidden by the Geocachers themselves. There is no organization that hides boxes but before a cache is published on a community volunteer, the so-called Reviewer checks the cache listing. There are many different types for geocaches the main types are:

Traditional Geocache: For these caches the coordinates are posted on So, you simply need to go there locate the cache, sign the logbook, and hide it again. 

Easy? Well, it depends. If you are looking for a geocache magnetically attached to a guiderail of a road, it’s easy. If you need to do three hours of bushwacking just to get there and then learn that the cache is hidden 30 feet high on a tree or deep in a cave, things start to get a little bit tricky. 

Multi-Cache: For these caches only the coordinates of the starting point of the hunt are published on the internet. At this starting point you get clues for the next point of the journey. Some multi-caches can be done in a few minutes, others need hours to be completed and include significant hikes. Some of these caches can only be done at night since you need to follow reflectors or use ultraviolet light torches to find your way. More than once multi-caches kept us busy from dusk until dawn. 

Mystery or Puzzle caches:  No coordinates are published at all for Mystery caches. You need to solve a riddle, do a calculation, or find hidden information in the cache description to retrieve the coordinates. And man, these riddles can be tough. Some cache owners seem to take pleasure from creating tasks that keep you working for hours before you finally manage to retrieve the cache coordinates. And not too seldom you find out that the coordinates just lead you to a location where you need to solve field puzzle to retrieve new coordinates that just lead you to the next waypoint… and another adventure begins. 

Logging a geocache works like this. As soon as you have found the cache, and you have been able to open the cache container, you sign the logbook and then you hide the geocache at the same hiding place so that also other geocachers can find it. Back home you are logging the cache on the internet to claim your find. For each log a find point is provided. Most geocaches are hidden by locals at beautiful places and by reading the cache description you can learn a lot about the location. 

The great thing about geocaching is that it combines outdoor activities (the actual hunt) with indoor activities (solving riddles and tour preparation). 

But there is more, there is a world-wide community of more than 3 million active players. Local, national, and international Geocaching Events are organized on a regular basis. During a trip around the world, we managed to attend geocaching events in Brazil and in New Zealand. Geocache events are a great possibility to get to know people, to get clues for so far unsolved mystery caches and to do nerdy things like discovering and trading Travel Bugs and Geocoins. 

Travel Bugs (TBs) are items that have a dog tag with a unique tracking code attached to them. With this code you can find a listing that describes the mission of the travel bug. So, for example you can attach a travel bug to a small item let’s say a small toy, drop it into a cache during a trip to a foreign country with the mission to travel to a cache in your hometown. 

Geocoins are trackables in all shapes, despite the fact that they also have a unique tracking code most of the time they are collectors’ items and owners just show them to other geocachers which can discover the geocoins by entering the tracking code on Tracking codes can be also found on cars, gear and clothing. In fact we also got to know a geocacher that had the travelbug logo together with a tracking code tattooed on his back – a little bit to discover such a TB.

I started geocaching in December 2007 and luckily it had a very positive impact on our marriage. My wife always wanted me to go hiking together with her and the kids. As soon as I started geocaching, I was out searching for geocaches all the time and Margit and the kids joined in on the hobby. In the meantime, our kids are grown up and no longer interested to look for Tupperware in the woods, but Margit and I are still crazy about our common hobby. However, Geocaching can be very addictive and when you are infected strange things start to happen and here are some examples.

In the beginning you think that the pen, a torch and possibly a Swiss army knife is sufficient to go geocaching. But then you find out that there are caches in via ferratas and you start to buy your first climbing gear. Then you discover that there are geocaches that require rappelling and suddenly you own a 80m (260 feet) long climbing rope. Oh, there is a trend for geocaches high up in trees, so let’s buy a telescopic ladder, a sling shot to get ropes into trees and a 12m (40ft) extendable fiber glass beam to fetch geocaches that are hanging in trees that cannot be climbed. By the way did I mention that there are geocaches on small river islands and under water?

Geocaching makes you learn strange skills. There are geocaches that require lockpicking skills (yes, I own a lockpicking kit). There are geocaches that require tree climbing (yes, I attended a one-day training course with a professional tree surgeon.) 

There are a high variety of geocaching riddles that use different cyphers and codes. And so you start to get interested in steganography and in esoteric programming languages such as white space, which only uses white space characters (space, tab & return).

But the best thing about Geocaching is that it takes you places and the game can be played all over the world. At the time this article is written I have personally found 6,722 caches in 44 countries. Places that we have visited include castles, ruins, WWII bunkers lost places, abandoned mines, ghost towns, forgotten fortifications, caves and many historic places. The lowest altitude cache I have found so far was in Death Valley’s Bad water basin (GCH657, -83m below sea level). The highest altitude cache I found so far was on Großglockner (GCK3BG, 3780m above sea level).

For many years my wife and I have been planning Geocaching trips to celebrate our wedding anniversary and more than once we ended up solving difficult night caches, while other couples of our age would spend a romantic evening enjoying a candlelight dinner. (Sorry, for being that nerdy.)

So, you will not be surprised that when Margit and I planned our trip around the world we had some special geocaches on our list that brought us to very interesting places. For example, we visited Pearl Harbor and the USS Arizona to as well as a few weeks later the freedom park in Hiroshima which marks the ground zero of the atomic bomb explosion over Hiroshima. Both places are historic landmarks and for that reason no physical cache containers are hidden there as a matter of respect. Nevertheless, to solve certain geocaches you need to collect information at such places and as a result you learn a lot about history. 

At such locations new cache types like the adventure lab caches are hidden. An adventure lab cache has no physical container. A special app guides you to different places of interest. 

You need to be within a certain distance to the place of interest before a question is shown in the app. The answer to the question should be only solvable when you are really at the location. This should help to avoid the so called armchair geocachers to collect points by using GPS spoofing. However, there are geocaching purists who claim that adventure lab caches are heresy and distract from the pure path of geocaching. 

Geocaching was started in the year 2000 when the so-called selective availability algorithm of the GPS system was switched off on 2. May. 2000 (Blue Switch Day) resulting in a lot higher GPS accuracy for civilian users. 

The first geocache was hidden by Dave Ulmer on May 3rd, 2000, close to Portland, Oregon. Serious Cachers are eager to complete the “Jasmer Challenge.” It is a challenge to find at least one cache hidden in every month since the first cache was hidden in May 2000. Unfortunately, geocaches hidden in 2000 and 2001 are getting really since abandoned geocaches without maintenance are archived. 

Thus, Margit and I tried to find as many old geocaches on our trip around the world as possible. The oldest ones were Lane Cove (GC3E hidden on 18 May 2000 close to Sydney, Australia) and Geocache GC46 (hidden on 25 May 2000 close to Wellington to New Zealand) further, on we visited Tombstone the oldest active geocache in Texas (GC62 hidden in September 2000.) By today we are only lacking two hiding months to complete the Jasmer challenge: June 2000 and August 2000. Unfortunately, there are only four (!) geocaches still active that have been hidden in August 2000 and twelve that have been hidden in June 2000. 

For 2024 we have planned two geocaching trips to historic Geocaches. One trip will lead us to Stockholm to find Match Stash (GC4D) the only European Geocache hidden in August 2000. And the second trip targets the visit of Europe’s First Geocache near Dublin, Ireland. 

Please keep your fingers crossed that these geocaches are still active when we get there.


Bernhard Baumgartner – “Baumi” holds a degree in electronic engineering and is active in the electrical industry since 1990. After various technical roles in the broadcast business, he joined the OMICRON group in 2006 to support the promotion of OMICRON Lab’s Vector Network Analyzer Bode 100. Since 2019 he is working at b2 electronics mainly taking care of the commercial aspects of selling equipment for VLF medium voltage cable test and diagnostics. Baumi is married since 1994 and has two adult children. If he is not working or geocaching he tries to find time for a myriad of other hobbies.