Moveable cache
From GeoWiki
Moveable caches are caches that are moved by geocachers. When the cache is found, the finder takes the complete cache to a new location, hides it and updates the coordinates on the website.
Moveable caches can be extremely innovative. There are a number of moveable caches that are used to play a giant game of Battleships!
Guidelines
Geocaching Australia welcomes all caches. Geocaching.com no longer accepts moveables, however there are some grandfathered moveables on their system.