Yes! You'll have offline access to your personalized guidebook in the ViaHero app, plus offline access to your custom maps, via the free Maps.me app. This means you’ll be able to navigate to all of your Hero’s recommendations, which are highlighted on the map, plus any place that exists in Google Maps—all offline!
While traveling, remember to turn OFF your data so you don't get roaming charges, but make sure the GPS on your mobile device is turned ON to be able to see your blue location dot on the map. Since your maps are all pre-loaded onto the app, you won't need any wifi or data to navigate.