TrekMe is an Android app to get live position on a map and other useful information, without ever needing an internet connection (except when creating a map). It's ideal for trekking, biking, or any outdoor activity. 

In this application, you create a map by chosing the area you want to download. Then, your map is available for offline usage (the GPS works even without mobile data).

Download from USGS, OpenStreetMap, SwissTopo, IGN (France and Spain)
Other topographic map sources will be added.

Fluid and doesn't drain the battery
Particular attention was given to efficency, low battery usage, and smooth experience.

SD card compatible
A large map can be quite heavy and may not fit into your internal memory. If you have an SD card, you can use it.

Features
• Import, record, and share GPX files
• Marker support, with optional comments
• Real-time visualization of a GPX record, as well as its statistics (distance, elevation, ..)
• Orientation, distance, and speed indicators
• Measure a distance along a track

For instance, all map providers are free, except for France IGN - which requires an annual subscription.

For professionals and enthousiasts
If you have an external GPS with bluetooth*, you can connect it to TrekMe and use it instead of the internal GPS of your device. This is especially useful when your activity (aeronautic, professional topography, ..) requires better precision and updating your position at a higher frequency than every second.

(*) Supports NMEA over bluetooth

Privacy
During a GPX recording, the app collects location data even when the app is closed or not in use. However, your location will never be shared with anyone and gpx files are stored locally on your device.

General TrekMe guide
https://github.com/peterLaurence/TrekMe/blob/master/Readme.md

Offline trekking USGS maps, OpenStreetMap, France IGN, Swiss Topo, and more.