Sudoku is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids that compose the grid contains all of the digits from 1 to 9. Wikipedia
To find the cache you need to complete the two Sudoku below.
N 51° ABCDE
W 008° FGHIJ
Have fun and happy hunting