AllTrails - Hiking & Biking
Free, with a Pro version at $49.99 for iOS or Android. According to the website, it includes 50,000 trail guides (United States & Canada) for a variety of activities such as fishing, biking, and hiking. You can cache trail information for offline use. The Pro version offers "National Geographic maps, verified routes, points of interest, and elevation profiles" and the ability to build custom maps, mark waypoints, and more. I found a good amount of Alaska content.