- Started in 2000 in Oregon by Dave Ulmer – days after GPSr technology became available to the public

- Number of caches worldwide in May 2008: 584 236.

- Types of caches: traditional caches, micro (small) caches, virtual (non-existent) cashes, trackable (hitchhiker) caches, multi-cashes (need to complete several steps to reach final cache), mystery caches (solve a riddle or puzzle to find cache), and others – the game is constantly developing!

- Bulgaria’s Geocaching site: geocaching-bulgaria.com

- The main gateway to everything related to geocaching: geocaching.com

- How geocaching helps maintain parks and public spaces: geocaching.com/cito/default.aspx

- All you need to know about buying and using a GPS unit: gpsinformation.net

- Online shop for a GPSr in Bulgaria: mobilebulgaria.com/shop/offers_type.php?product_type=10