As mentioned on the main page, to qualify for one of the Explorer Challenge caches you need to find caches in the same number of grid squares as the number of the Explorer map.

From personal experience I know how time consuming trying to determine which of 600 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.

For the purposes of these challenges 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 number of GSAK Macros have been written which produce a web page of your finds, example output shown below.

When you have found the relevant number of 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, please check individual challnege caches for the particular requirements set by individual cache owners:

1. List the cache codes and names in corresponding grid reference order in your found log
2. Create a public bookmark list
3. Send the GSAK Macro generated file to the cache owner or add it to your profile page
4. Send the cache owner "My Finds" Pocket Query and ask them to run the GSAK Macro for you and let you know if you qualify and if not which squares you still need to find a cache in to qualify