Users doing some route hiking and back country exploring can check out ViewRanger, an offline mapping, navigation, and guided trail app for Android devices. ViewRanger comes with a variety of open source map data, with detailed topographic maps from the USGS, Acuterra, and others available as in-app purchases. ViewRanger uses GPS and can save your maps for offline use, with provision for route guides, track recording, sports computing stats, and location sharing.