Keep the map with no signal
Your phone loses signal on the far side of the pass, just when you need the map. Download New Zealand before you leave. Then the map, route planning and the voice that calls your turns all work with no signal.
1Open Menu, then Offline
Tap Menu at the top left of the screen. Then tap Offline at the top of the menu. This tab holds everything you can keep on your phone. The downloads are big. Do this at home on wifi before you leave. Keep your phone on its charger if you can.

2Download the whole of NZ
The first card says Download NZ. It holds the map, the hills and offline routes for the whole country. Tap Download. Keep the app open until it says Downloaded: the app runs fast and works fully offline. If it stops, tap Get the rest to carry on. You won't lose what is already done.

3Add satellite if you want it
When the download is done, a Satellite (optional) line shows on the card. Satellite is photos of the ground taken from space. You don't need it for the map or for routes. It is big, and its size is on the line. Tap Download on that line if you want it.

4Leave Map source on Auto
At the top of the Offline tab, tap Advanced to see Map source. Leave it on Auto. Auto uses the online map when it can. When nothing comes through, it moves to your downloaded map by itself. Then it moves back. Offline only always uses your download. Online only never does. The line under it says which map it is using now.

5Head out and tap Nav
With the NZ pack, maps, hills, routes, saved routes and alerts all work with no signal. Tap Nav, and it still says each turn out loud with your phone's own voice. You can plan a new route out there too. Live weather and search still need a signal. Check them before you lose it.

Good to know
Your maps are kept in your phone's web browser. If you clear your browsing data, they go too. On a phone, the app may offer to download the maps and route data for you. Tap Download on that card, or Not now. Stop ends a download part way.
Also in the app: turn by turn navigation, campsites and huts, and Plan with AI. It plans routes for eight kinds of vehicle, from an enduro bike to a motorhome.