Google has said it's allowing users to download maps and turn-by-turn directions of a particular area for use when there's no Internet connection.
This new capability is being rolled out to Android and iOS a little later.

Now you can download an area of the world to your phone, and the next time you find there’s no connectivity—whether it’s a country road or an underground parking garage—Google Maps will continue to work seamlessly. Whereas before you could simply view an area of the map offline, now you can get turn-by-turn driving directions, search for specific destinations, and find useful information about places, like hours of operation, contact information or ratings. Google Maps and Directions Now Operate In Offline Mode Once Downloaded [googleblog.blogspot.com]