Puzzle cache
From GeoWiki
A Puzzle cache is a geocache which requires the geocacher to solve a puzzle in order to find it.
Puzzle caches are categorised as Mystery caches or Unknown caches on the cache listing websites.
Puzzles vary from the simple to absolutely diabolical. Difficult puzzle caches can take weeks to solve.
007 is an example of a Mystery Cache in Adelaide.
i!8: GET SMART now archived, but reputed to be one of the hardest puzzle caches in Australia. There is a secret behind-the-scenes look at i!8: GET SMART for wiki readers.
Geocaching Australia has a collection of useful tools in the Toolbox that may help to solve or create Puzzle caches.