From Bushwalk Australia
Bush Bashing is the activity of bushwalking through an area without following any visible track and therefore requiring the use of some other form of navigation (eg. compass, GPS). It implies that there is vegetation of at least some density such that it needs to be pushed (bashed) through in order to proceed, but the term is occasionally used by some people even if there is no actual 'bashing' required to proceed.
See also: Scrub Bashing