This is a variant of a Sudoku puzzle: You need to put a digit from 1 to 9 in each of the small squares below so that:
Each of the 9 rows contains each digit from 1 to 9 exactly once.
Each of the 9 columns contains each digit from 1 to 9 exactly once.
Each of the 9 3x3 blocks (bounded by the thick lines) contains each digit from 1 to 9 exactly once.
In a normal Sudoku puzzle, I'd fill in some numbers to get you started. Instead, I'm showing you all of the places where two squares that are adjacent (horizontally or vertically, not diagonally) contain numbers that are numerically consecutive: If there's an arrow from one square to an adjacent one, then the number in the second square equals 1 plus the number in the first square. For example, if a 4 is next to a 5, there'd be an arrow pointing from the 4 to the 5. If there's no arrow, then the numbers differ by 2 or more.
Once you've filled in the grid, use the numbers in the six squares labelled from A to F to get the actual coordinates of the cache:
N 40° 46.ABC W 124° 08.DEF
If you think you've figured out the coordinates, you can check them with certitude:
You can also see who else has solved the puzzle. Note: You can remain anonymous if you want to; incorrect guesses are always anonymous. (Puzzle makers, you can create your own certitude links here.)
Congratulations to the first certified solver, kanchan, and the first finders, Phobos+Demos.
If you're ever on Prince Edward Island in Canada, you can use the solution to this puzzle to find a cache there: #36 Kudos!