A. Unfortunately, no. The basemap in the GPS III is permanent and cannot be updated or upgraded. Hardware provisions are not incorporated into the design to support additional data, and additional maps cannot be loaded into the unit. It is important to keep in mind that the map contained within the unit is intended to serve only as a general reference to surrounding features and should not be used as the sole means of navigation. Although we strive to provide the best product/features available, GARMIN does not guarantee the accuracy of the map data.