CalTopo

CalTopo is the strongest candidate in this batch for examining why a route may be hard, not merely where it goes. Measurement tools expose distance, elevation, slope and aspect; overlays add terrain, land ownership, current conditions and public-safety context. A planner can draw alternates, inspect profiles, print a map and synchronize objects to the mobile app. Paid users can download chosen layers, and downloaded elevation supports slope shading even while offline.

Its analytical appearance can tempt users to assign more precision than the source data warrants. CalTopo explicitly warns that slope shading is not an absolute description of every small feature, and real-time layers still require connectivity. Cached tiles are not a dependable substitute for an intentional download. Check the legend and source date for each overlay, include a surrounding buffer, and bring a printed map for remote travel. Avalanche terrain, cliffs, river crossings and private access need discipline-specific verification rather than a single colored layer.