Organic Maps is super awesome. The routing feature is really good, too. It even works on Apple CarPlay! There are some glitches to be aware of though: Routing across region borders is often broken.
Also, a warning about OSM in general: Do not blindly trust it. Map data can be very out of date in some places, especially on remote-ish hiking trails.
Also, a warning about OSM in general: Do not blindly trust it. Map data can be very out of date in some places, especially on remote-ish hiking trails.