The listed coordinates are for the trailhead at the northern entrance to the McKay Community Forest. The cache is about half a mile away; to get its coordinates, solve the puzzle below.
A few years ago, I discovered a YouTube channel, Cracking the Cryptic, which features 2 British puzzle champions, Mark Goodliffe and Simon Anthony, solving logic puzzles and cryptic crosswords. From there I learned about a German website, Logic Masters Deutchland, where people can publish their own puzzles and solve ones created by others. Many of these are Sudokus with extra constraints, such as sandwich clues, killer cages, X-sums, kropki dots, German whispers, and thermometers. If you go to the Cracking the Cryptic channel you can find many examples of these.
People keep inventing new constraints, some of which get used in many puzzles and some of which are never seen again. I've invented a few myself, of which my favorite is "mountain sudoku". So when I was ready to hide another puzzle cache, I decided to make it an easy mountain sudoku puzzle. (You can see my previous mountain sudokus here.)
As in a normal sudoku puzzle, you need to fill a 9x9 grid with digits from 1 to 9, so that every row and column, and each of the 9 3x3 boxes defined by the thick black lines, contains each of the 9 digits exactly once. For such a filled grid, I define the "mountain" as follows: The peak of the mountain is the cell in the central box which contains the digit 9. (A "cell" is one of the 81 small squares in the grid.) The mountain consists of all cells which can be reached from the peak by repeatedly moving from a cell to a horizontally or vertically adjacent cell containing a smaller digit. If you think of the digits as heights, then any cell that you can reach by going "downhill" from the peak is part of the mountain.
In the example below, the peak is shown with dark shading and the rest of the mountain is lightly shaded. The red line shows why the 3 in row 7, column 6 is in the mountain: You can move from the peak to the 3 along the red line, with the digits decreasing along the line.
For this cache's puzzle, the mountain consists of the shaded cells in the grid below. You'll need to find the peak and the other digits for yourself.
Note: Unshaded cells are NOT supposed to be in the mountain. So if, for example, you have a 3 in a shaded cell and a 2 in a horizontally or vertically adjacent unshaded cell, then you haven't solved the puzzle, because the 2 would also be in the mountain.
You can either print this out and solve it on paper, or you can use the online tool used by Cracking the Cryptic, Sven's SudokuPad. For help using SudokuPad, click on the 3 white lines at the top left and then on Home/Help.
Once you've solved the puzzle, use the digits from the squares labelled A through E to form the final coordinates of the cache:
N 40 46.A0B W 124 07.CDE
If you think you've figured out the coordinates, you can check them with Certitude. I highly recommend this, since it's hard to get accurate GPS readings in the forest, and Certitude will give you a big hint.
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 finders, Robessa.