A Military Decon Box in the woods.
Very hard to open and close, careful not to get the strap caught in the lid when you shut it.
Too hard for most kids to close up...Needs adult supervision.
Make sure it snaps closed, otherwise it'll be full of water when it's next found.
Room for small trading items and travel bugs 1 1/2" x 3" x 4"
Note: Serious Buchwhacking Required to get to the GZ!