Offline maps on Apple Watch for trail running

Deep in a valley, with no signal and the phone in the car, an Apple Watch has exactly the map data someone put on it beforehand: none, unless you planned for it. Following a trace on a blank background works, and many runners never need more. But when the path forks three ways and the trace runs between two of them, a real map under your dot is what tells you which one.

This guide explains what Ridge downloads, where it lives, and how to make sure it is there when you start.

Two layers: the trace, and the map under it

Free, always: the trace, your position, the direction of travel, distance markers and the elevation profile. This is drawn from the GPX itself and needs no network at any point. It is what off-route alerts and notes work from.

Ridge Pro: the route’s map, meaning the topographic map tiles covering a corridor around the trace, downloaded to the iPhone and to the watch. Offline, the watch draws them under the trace like it would online. Paths, contour lines, streams, buildings, the things that let you place yourself.

Which map

• In France, the IGN map (Plan IGN, the current edition of the national mapping agency’s topographic base, under an open licence). The same paths, contours and place names as on the paper 1:25 000 series, which is what most French trail runners already read.
• Everywhere else, a worldwide topographic map with contour lines, built from OpenStreetMap data. It is what you see on the route’s map in Ridge outside France, and the downloaded version is made of the same tiles.

Ridge picks the source from where the route is. A route across the Franco-Italian border gets the French map on the French side and the worldwide map on the other; nothing to choose.

Size and download

The map covers the route and a margin around it, at the zoom levels the watch actually uses. For a 20 km mountain route that is typically 30 to 50 MB. A flat route is smaller; a long alpine loop with dense contours is bigger. Ridge shows the estimate before you confirm.

Each device downloads its own map. The iPhone fetches its copy in seconds. The watch downloads its own straight from the internet, without going through the phone, from the route’s screen on the watch. On Wi-Fi it is quick, and an interrupted download resumes where it stopped.

Ridge tells you, per route, whether the map is on the iPhone, on the watch, or still downloading. The route’s readiness line is the thing to check before you leave the car.

The map belongs to the watch

Once the map is on the watch, it stays there until you remove it on the watch. The iPhone cannot reach into the watch’s storage, so deleting a route’s map on the phone frees the phone’s space, not the watch’s. This is deliberate: a watch that lost its map because the phone tidied up would be worse than no map.

To free space on the wrist, open Ridge on the watch and remove the map there. Space on an Apple Watch is generous for this: a dozen mountain routes fit in half a gigabyte.

Without Pro

The iPhone shows online maps (they need signal) and the watch shows the trace on a plain background. Everything else, navigation, alerts, notes, recording, is identical. Pro is for the day you go somewhere the map matters and the signal does not exist. It is also what pays for the tile hosting outside France, which is why it is not free.