When people explain what geocaching is, it's normally something like "You get coordinates to a place, you go there, you find the box, you sign the log". This is how a Traditional cache works, and this is by far the most common cache type. There are, however, a number of other types as well.
One of my favorite things with geocaching is that different caches can be so different, and one of the things that makes it so is that there are different types of caches. This particular cache is a "challenge cache" (which is a subtype of the Unknown cache) which means that you need to do something before you are allowed to log it. In this case, you have to log at least one cache of each of the types listed below.
The types below are not quite all the types there are, but they are all types of which there are at least one active cache in Östergötland at the time of writing.
This cache is really at the posted coordinates, but in order to be allowed to log it, you must first complete the challenge requirements: log at least one of each of the cache types below. Finds made before this challenge was created may be counted, as well as finds in other countries and finds that have been archived.
Traditional caches are the simplest type of cache. You get the coordinates to where the box is, and you just have to find it.
Multi-caches are kind of like traditional caches, but more than once. The coordinates you get are not the final location but a place that needs to be visited to find the box. In the first location you may find a box with new coordinates, or the cache description may tell you how to calculate new coordinates using information found in that spot. A multi is a good way to guide a cacher around a trail or showing an interesting spot where a cache can't be hidden for practical reasons and then guiding the cacher from there to the final place.
Unknown caches can be more or less anything. The coordinates you get are rarely the ones where the cache is (but can be, as with this cache). Instead, the coordinates for an unknown cache (commonly known as a "Mystery cache") tell you in what general area the cache is, but not its exact location. To get the exact coordinates you must first solve some kind of puzzle. In some cases, part of the problem can even be to find the puzzle. Most mysteries don't require you to visit the posted coordinates, but there are exceptions (usually known as "field puzzles").
Letterbox hybrid caches are somewhat like unknown caches and somewhat like multi-caches. The reason for the "hybrid" part of the name is that this cache type plays on a much older game than geocaching called "letterboxing" where you get a description of how to move from a starting place to a hidden box (traditionally containing a rubber stamp for stamping your personal log book). Like with unknown caches the variation is large, so read the cache desctiption for details for each letterbox, but often you need to follow a written description of landmarks to get to the cache location.
Whereigo caches are what multi-caches would have been if geocaching had been invented today instead of before smartphones and intelligent GPS:es. A whereigo gives you a cartridge (a small "program" that you feed into an app on your smartphone or GPS) that will then tell you what the next destination is and give information or ask questions along the way.
Earthcaches are different from all the above cache types in that there is no actual box to be found. Instead, you are directed to a place of geological interest. Here you will be required to find answers to a few questions about the site which you need to send to the cache owner, instead of signing a log.
Virtual caches work in a similar way to earthcaches in that there is no actual cache. A virtual cache can be about anything, though, and may not even require and questions to be asked. Virtual caches have been discontinued and may not be created anymore, but the ones that are out there can still be logged.
Event caches are also different from most other caches. There is no hidden box here either (usually, at least), but there is usually a log to be signed. Event caches do not only have a place, but they have a given date and time as well where geocachers will meet and get to know each other. Sometimes events are purely social happenings where you can get to know other local cachers while other events offer some organized activity as well (competitions, lectures, demonstrations, etc).
