difficult terrain
Any type of terrain that would be difficult to cross such as mountainous and hilly terrain, heavy swamp, or a thick forest. Movement over long distances through Difficult Terrain takes 2× as long. This does not apply in combat and action scenes though the Mediator may apply other penalties as appropriate.
Keyword
Salvage Union Workshop ManualPage 69
Any type of terrain that would be difficult to cross such as mountainous and hilly terrain, heavy swamp, or a thick forest. Movement over long distances through Difficult Terrain takes 2× as long. This does not apply in combat and action scenes though the Mediator may apply other penalties as appropriate.
Source: Salvage Union Workshop Manual, p. 69