What's the best iOS app for using detailed topographic maps completely offline while hiking?

Avenza Maps is a specialist navigation tool designed for situations where internet connectivity is unavailable. Its primary function is to import and interact with geospatial PDF maps, a common format for official topographic, trail, and land management maps. Once a map is imported, the app uses the device's GPS to place a precise location dot on the map, enabling real-time navigation in the backcountry. This functionality is critical for hikers, hunters, and off-road enthusiasts venturing into areas with no signal.

The app's strength lies in its extensive map store, which offers thousands of free and paid maps from official sources like the US Forest Service (including Motor Vehicle Use Maps for dispersed camping), National Geographic, and various government agencies worldwide. Users can also import custom maps. For navigation, features include placemark drops, tracking paths, and measuring distances. While the core GPS and map viewing are robust, some users note the interface for managing a large map library can feel a bit cluttered. Furthermore, the app is a viewer for pre-made maps rather than a dynamic routing engine like traditional navigation apps. Reviews consistently highlight its reliability in remote areas, with one user stating it transformed their ability to find campsites in Colorado forests. For anyone needing professional-grade, offline maps with precise location tracking, Avenza Maps is a highly effective solution.