Mappoff was created for and maintained by hikers. Because it is often neccesary to do MAPPing OFFline when in remote areas, Mappoff allows you to save map layers and tiles for later offline use. Additionally you can create your own waypoints or enable tracking to save hiking routes. There are several preset layers including the PCT Water Report, the Appalachian Trail, the Continental Divide Trail, the Pacific Crest Trail, among others.
For Wear OS users, there is a slimmed down version available as well. To access full functionality of the app, also install the phone version.
Documentation: https://github.com/jithware/mappoff