A navigation device comprises a processing section (520); and an output section (530) for providing an output responsive to the processing section; wherein the processing section (520) has access to map data (540) and avoidance data (550), the avoidance data (550) including information for identifying undesirable locations, and the processing section (520) is arranged to: receive location information representing a geographical location and direction of travel in relation to the map data (540); and establish, based on the location information and map data (540), whether the geographical location and direction of travel approach a navigation decision point having a plurality of navigation choices, where each navigation choice corresponds to an onward route leaving the navigation decision point; determine, based on the map data (540) and avoidance data (550), for at least one onward route leaving the navigation decision point, whether the onward route unavoidably includes an undesirable location; and provide result information to the output section (530) based, at least in part, on the determination.