On your travels, load your Google Maps once when you have access to Wifi and you'll be able to zoom in/out as you desire.
Note, you won't be able to use the to/from destinations to get a step-by-step guide offline but again, if you load it when your phones online, you'll be able to follow the step-by-step directions when your phone is offline.
Finally, ever wanted to check out where exactly you are when you're flying? Your phone's GPS works even when on Airplane Mode.
Give it a try!
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