One of the unsung features of Apple's iOS 6 Maps app is that it uses vector-based -- rather than raster-based -- maps that chew up less bandwidth and can be stored in a much smaller amount of memory. Many iOS 6 users are now finding that they can actually use the Maps app without a data connection, provided that they've "visited" the areas of interest while online to pre-cache a lot of the map information.
The main difference between vector and raster maps is that vector maps are mathematically described and resolution independent, while raster maps are essentially simple flat images that are loaded into a map app. Using the mathematical description of locations allows Apple's Maps app to use up to 80 percent less bandwidth and store much more map data on the device.
After reading a post about this capability on AppleInsider, I did a quick test of iOS 6 Maps with my iPhone in Airplane Mode. What I found was that I was able to peruse maps at street level of accuracy offline, provided that I had previously looked at those locations while online to load the data. For example, the images in the gallery below show my home location, a state-level map of the Western US, most of South America, street maps of Ushuaia, Argentina and a satellite view of a neighborhood in Auburn, Wash., that I lived in as an child. Note that the Airplane Mode indicator is present in all of the screenshots.
Are the offline maps perfect? No, but if you're planning a trip and want to have street-level maps available for use offline, it's now possible to pre-load those maps by simply looking at them online ahead of time. The cached vector information will give you something to look at even if you've turned off cellular data on your iPhone to avoid data roaming charges.