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Explorer 224 Challenge Mystery Cache

Hidden : 04/14/2013
4.5 out of 5
1.5 out of 5

Size: Size:   regular (regular)

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Geocache Description:

This is cache in the Explorer Challenge series, originally conceived by PetersfieldPoodlePosse, and based upon British Ordnance Survey grid squares as depicted on Explorer maps.


You can also check this Web Site for more information about the series,

To complete this challenge all you have to do is find a total of 224 different caches; how difficult can that be?

What is the Explorer 224 Challenge?

The cache is called the Explorer 224 Challenge because each of the 224 different caches you need to have found to qualify must be in a different British Ordnance Survey grid square as depicted on the Explorer 224 Corby, Kettering & Wellingborough.
The caches can be of any type, previous finds qualify (including those finds now archived and events attended (even if you were the host)), in fact just about any cache other than those you have placed yourself (more on that later) can be counted.

The grids on the map "start" in the north west corner near Medbourne at SP 80000 95000 and "finish" to the south east of Bourne End at TL 03000 60000, so giving a possible 860 squares in total in which you need to find a cache in 224 different squares to qualify, which in turn equates to just over 25% of the possible squares available.

It can be time consuming trying to determine which of 860 squares of an OS map a cache qualifies for, although of course the British Grid reference is given at the top of each cache page just below the main co-ordinates shown in bold, as circled below.
Cache Example

For the purposes of this challenge the published co-ordinates of all caches, including Unknown/Mystery and Multi caches are those that are to be used when determining which square a cache counts towards.

To help those of you that want to plan your finds a GSAK Macro has been written which produces a web page of your finds, example output shown below. I recommend this option as the macro takes only seconds to run.

224 Qualifying grid

When you have found the 224 caches you need to provide proof of that fact to be eligible to claim a find on the cache; this can be via one of any number of different methods you may have available:

  1. List the 224 cache codes and names and corresponding grid references in your found log
  2. Create a public bookmark list
  3. Create a Spreadsheet grid of your finds and attach an image of it to your log
  4. Attach the generated GSAK Macro image to your log
Any finds without proof of qualification will of course be deleted! Have fun!

Many thanks to PetersfieldPoodlePosse for allowing me to use the Explorer Challenge concept and writing the GSAK macro specially for me. Also I would like to thank Firemountain24 helping with this cache page. I understand that there may be problems with this macro if you are using a 'Mac'. If would like help with GASK please contact me and I will only be to happy to help..

Additional Hints (Decrypt)


Decryption Key


(letter above equals below, and vice versa)