Prepper Stashes are scattered throughout the world of Far Cry 5. You can find them as you explore but I talk to any citizen I rescue. Some of them will have an icon above their head indicating they know the location to either a prepper stash or even an enemy outpost.

In order to gain the loot from a prepper stash there is usually some sort of puzzle to solve. If you've played Ubisoft games before, you'll find these puzzles easy to solve. If not, they can be tricky at first but once you can anticipate their logic you'll know what to look for.

This video shows the location of the Dumpster Diving stash and how to access it. You must possess the grappling hook in order to proceed with this part of the game. It took me some time to figure this one out since it had a few different puzzles to solve. If this video helps you let me know in the comments below, if it doesn't, feel free to let me have it.