How to have GPS without cellular data on your smart phone

There are at least 2 different ways of getting maps on your mobile phone for GPS navigation without having to use cellular data:

  1. download an app that has an entire map set such as TomTom
  2. Google maps app lets you download a portion of a map for “offline access” iOS   Android

Of course you could use a stand alone gps or paper maps too. But who wants to buy or carry the extra things?