GPS use overseas without data

You can’t use Apple Maps, Google Maps or Waze without data to load the maps from. There are GPS apps available in the App Store that store all map data on your phone; they are not free.

If you need to use your iPhone as a GPS, without using data - then you must use an app that offers offline navigation. An app that can download maps. Apple Maps cannot do this.

Google Maps can be used offline, and can be downloaded and used for free in the App Store.

→ You can see how to use offline maps here.

Another app is TomTom GO. The app is not free, a one-month subscription costs $9.99. But then you can also get and reliable navigation and offline maps.

→ Download TomTom GO from App Store

There are probably more apps, but these are the two apps I know and can recommend.