This could be a useful app for packrafters, canyoneers, fishers, etc. It shows rivers, streams, and tributaries in different colors, plus USGS streamflows if you have cell coverage:
http://www.spokesman.com/stories/2017/oct/01/outdoor-tech-detailed-waterways-info-and-gps-in-si/
— Rex
PS – Is an app gear in the BPL taxonomy?

