Originating as a method of carrying out collegiate pranks at MIT in America, roof and tunnel hacking has become a sport of its own. In principal it is a fairly simple idea. Participants navigate their way through utility tunnels and across roofs, usually in unauthorised expeditions. Small maintenance tunnels and high, inaccessible roofs offer thrill seekers the opportunity to find their way through difficult routes in strange locations. The term is generally synonymous with discovering rarely-seen parts of American university campuses, but can be used to refer to urban exploration anywhere. .