What are overlays?
Overlays work on any map layer and provide a wealth of additional information to help you plan your next adventure.
Photos - displays geotagged photos across the trail map so that you can get a sense of what to expect and where.
Waypoints - displays geotagged waypoints across the trail map so that you can easily find landmarks, attractions, junctions, trailheads, and more.
Nearby Trails - drops map pins for nearby trailheads so you can see other trails are in the area as well as other access points.
US Contours - adds contour lines and slope angle shading to any map layer.
In addition to the Photos, Waypoints, Nearby Trails, and US Contours overlays, there are four real-time overlays that are exclusive to Pro members:
Heatmap (Pro feature) - reveals a composite visualization of all the user recordings tied to any trail. Easily find the most popular routes, or seek out the less-traveled paths that other community members have taken.
Fire History (Pro feature) - displays recent fire activity, including year and incident name. Color coded by recency with red indicating the most recent and yellow the oldest.
Weather (Pro feature) - displays real-time satellite and radar weather data over any map layer.
Air Quality (Pro feature) - displays a real-time air quality index over any map layer. Know what the outdoor air quality will be before you hit the trail! Color coded with green indicating the cleanest air and red indicating the most polluted.
These overlays can be found by tapping on the Overlays button in the lower right corner of any map view screen.
To read more about map layers, please click here: http://support.alltrails.com/solution/articles/222523-what-are-map-layers