**This is a 2 stage multi cache. You need to solve the puzzle, which you can do at home, then visit the posted coordinates to find a number to pass the checker and learn the final coordinates. Posted coordinates are parking coordinates, final is less than a 1/4 mile walk.**
The purple cow has another puzzle for you on its way home. You can solve the tetromino puzzle any time, but will need to add the number 'X' to the end of your solution. At the posted coordinates is a statue featuring 'X' number of figures fishing.
As for the puzzle, you need to place one 'X' and one 'O' into every tetromino (four square shapes you find in Tetris). The 'X's cannot touch another 'X' and the 'O's cannot touch another 'O' - not even diagonally for either. Some are placed already to get you started.
For your solution, reading from top left to right, then along each row going down (like english reading) list the grid reference for each X with the letter first, then number, with no spaces between each entry. Include the 3 Xs you start with in your answer.
As well as solving all the 'X's, you'll need to solve almost all of the 'O's as well to learn the solution but you don't need to list them in the checker.
As an example, the starting state would be described as "B1F5B8".
You can validate your puzzle solution with
certitude.
The final location is a short walk from the posted coordinates and they are the best spot to leave your vehicle. The final hiding spot is up in a tree that is climbable, or you can use a reaching pole to get it, since it is not tethered.
A few years ago some people lived in a tent in the park by the river bank close to the final for a little while. They didn't cause any trouble and are not there now, but know there's a chance someone might be chilling next to the river within earshot but not too near to the final. The final is on city property and placed with permission. You will be in tree cover and not need stealth.
By the way, if you see a geocache around Pocatello with "UP!" in the title, it probably needs a reaching pole.