You land with a low battery, a hotel address and a station name that looks nothing like the one you practised saying. The useful travel setup is small: know where you are going, understand the transport choices, and have a way to ask an ordinary question.
“Must-have” here means a shortlist for preparing that trip, not a universal ranking. These three roles complement one another, but their coverage and offline limits still matter. Prepare for the place you are visiting, not for a promotional claim about travelling anywhere.
Google Maps: an address and an area
Google Maps is the candidate for keeping the destination and surrounding area at hand. Its iPhone offline-map guide documents downloading an area before losing connectivity. It also says downloads are unavailable in some regions.
The important boundary is transport mode. The same guide says offline public-transport, walking and cycling directions are unavailable; offline driving lacks traffic information and alternative routes. A downloaded map should not be mistaken for every connected navigation feature. Read the Google Maps audit before treating an offline area as a complete arrival plan.
Keep the full address in a form you can recognise and show someone. Identify the station or stop separately from the accommodation name. That preparation makes an app result easier to check against the sign in front of you.
Citymapper: understand the transport choice
Citymapper is the transit-focused candidate when it covers your destination. Its current Store listing describes comparing transport options, step-by-step guidance and status alerts. It is a free download with purchases and lists city coverage as something to check.
