Letterboxes

I just heard about letterboxes today and thought it was the coolest thing! Letterboxing is the hobby that combines art, puzzle solving, and orienteering. Basically letterboxes are small, weatheproof boxes that are hidden somplace public like a park or mueseum and clues to their location are published in a catalog or on a website. The letterbox has a notebook and a stamp inside and the person who finds it uses their own stamp to leave an impression in the notebook and takes an impression from the found stamp. Here's an example of the stamps and pages from Simon Litton's letterbox journal

There are quite a few places in the Bay Area to hunt for letterboxes - maybe I need a new hobby and should start collecting stamps.