How to read a topographic map and navigate

Navigation is not about guessing where north is: it is about knowing where you are on the map at all times. Contour lines, scale and a simple compass cover almost everything.

Scale

On a 1:25,000 map, one centimetre represents 250 metres on the ground; at 1:50,000, it represents 500 metres. For walking, 1:25,000 is the useful standard because it shows paths and terrain details.

Contour lines

• Each contour line joins points at the same altitude; the contour interval (often 10 m) is shown in the key.
• Closely spaced contours mean a steep slope; widely spaced contours mean gently sloping ground.
• Concentric closed contours indicate a summit; a ‘V’ pointing uphill marks a gully, while one pointing downhill marks a spur.

True north and magnetic north

A compass points to magnetic north, which does not exactly match true north on the map. This difference is called magnetic declination and varies with location and year; on the Iberian Peninsula it is a few degrees, enough to take you off course over long distances. Check it for your area and apply it when plotting bearings over long distances.

Taking a bearing

1. Place the edge of the compass on the map so that it joins your position and your destination.
2. Turn the compass housing until its lines are parallel to the map’s meridians, with N pointing towards north on the map.
3. Read the degrees at the index mark and correct for declination.
4. Holding the compass, turn until the needle lines up with the orienting arrow, then walk in the direction of the direction-of-travel arrow, using visible landmarks to guide you.

Using your mobile as a GPS: yes, but with rules

Your mobile’s GPS receiver works without mobile reception; downloading the map is what requires reception. That is why you need to download it beforehand. Carry a power bank, switch on power-saving mode and protect your phone from the cold, which greatly reduces battery life. And do not rely on a single device: a paper map and compass do not run out of battery.

The National Geographic Institute publishes Spain’s official topographic mapping, which is useful for planning routes and printing a map of the area.