Letterboxing is a outdoor recreational activity which combines collecting, puzzle-solving, and treasure hunting.
Briefly, letterboxing enthusiasts hide and hunt weatherproof containers in remote or scenic places. Each container holds a guestbook, a rubber stamp and stamp pad. The planter of the letterbox distributes clues to its location; solution of these clues may require a combination of skills such as mapreading, orienteering, and puzzle-solving.
Letterboxers carry their own stamp book and personal stamp when hunting for hidden boxes. Upon finding a letterbox, they will impress their own book using the found stamp, and leave their own stamping or personalization in the letterbox guestbook.
Letterboxing has its roots in Dartmoor, England, in 1854.