The Milton Keynes Boundary Walk is a circular walk approximately 65 miles long around the boundary of the Milton Keynes Unitary Authority; it is waymarked with the Oakleaf symbol.

In 2012 a group a local geocachers divided the walk into sections and set a series of over 300 caches along the boundary.

More information about the walk and caches can be found at the website Caching the Boundary.

The turquoise section of the walk is approximately 3.8 miles long. It starts at the north eastern edge of Oakhill Wood, heads west to the Stratford Road, and from there goes north west past Calverton, before heading north east and finishing near the outskirts of Stony Stratford.

There are 17 caches in this section, consisting of 15 traditional caches, 1 puzzle cache and 1 bonus cache (which contains a letter for the Gold Super Bonus cache).

Each (non-bonus) cache contains a letter, and some of these letters, in combination with the corresponding cache’s final coordinates, are needed in order to calculate the final coordinates of the bonus cache. The bonus cache is hidden near the middle of the turquoise section.

The turquoise section of the Milton Keynes Boundary Walk is all on quiet public footpaths, apart from a short segment along the Stratford Road. This segment can be quite busy, with fast moving traffic, so please take care.

If you start your walk from the beginning of the turquoise section then the closest car parking is at car parking.

To make the turquoise section slightly more challenging this one is a puzzle cache.

The cache is not at the given coordinates.

When this cache was first set it was a simple (to me anyway) ‘crypto’ puzzle cache. It was found three days after publication, and further finds followed on sporadically after this.

But then I heard a rumour that no-one had actually solved the puzzle, they had just deduced where the cache was likely to be, gone to that location and found the cache.

This is of course a valid approach to finding a puzzle cache, but not quite what I had in mind when I set the puzzle.

So rather than waste a decent puzzle, I created a separate puzzle cache (Total Mix-up) which uses the original puzzle theme, and changed this puzzle cache so that you have to work out where it is hidden by thinking like I did when I set it, and then making some deductions. If you find it difficult to think like me then look at the hints for the assumptions you need to make.

Note that the cache closest to GZ at the time the puzzle was set was Who Loves Ivy? at these coordinates.

You are looking for a black Turtle Tub.