Topographic maps look intimidating at first, with their tangle of brown lines, but those lines — contours — are the single most useful thing on the map for a hiker. A contour line joins all points of equal elevation, so reading them tells you whether you are walking up a gentle slope, a steep cliff, or along a flat ridge, before you ever set foot on the trail.

Each contour line represents a fixed height above sea level, and the vertical gap between neighbouring lines is called the contour interval. That interval is printed in the map legend and is the same across the whole map sheet. If the interval is 10 metres, then crossing five lines means you have climbed or descended 50 metres. Index contours, usually drawn thicker and labelled with their elevation, appear every fifth line and make it easy to count height without doing arithmetic on every line.

The spacing between contours is where the real information lives. Lines packed tightly together mean steep ground, because a lot of height changes over a short distance. Lines spaced far apart mean gentle ground. If lines merge into a single thick line, you are looking at a cliff or a very steep drop. Before a hike, trace your route and look for the sections where lines bunch up — those are the sections that will feel hardest, whatever the distance says.

The shape of the lines tells you about landforms. Contours that form a V shape pointing uphill indicate a valley or stream channel, because the line bends upstream where the ground dips. Contours forming a U or V pointing downhill indicate a ridge or spur. Closed, roughly circular contours mark a hilltop or summit, with the innermost circle being the highest ground. Recognising these patterns lets you match the map to what you see: a stream on your left, a ridge on your right, a summit ahead.

A saddle is the low point between two hills, shown as a pinched gap between two sets of closed contours — a useful landmark and often a natural route across a ridge. A re-entrant is a small valley running into a hillside, shown by contours bending inward. Learning to spot saddles, spurs, and re-entrants turns a flat map into a three-dimensional picture in your head, and it helps you stay oriented when the trail is faint or the weather closes in.

Before your first hike with a topographic map, practise at home. Pick a route you know, or a local hill, and study its contours. Then go and walk it, comparing the ground to the map as you go: notice how a tight bunch of lines felt on your legs, how a V-shaped valley matched the stream you crossed. This habit builds a mental library that makes every future map easier to read. Bring a compass too — contours tell you about height, but a compass tells you which direction you are facing when the path is unclear.

Beginners make a few predictable mistakes. The first is ignoring the contour interval: two maps with different intervals can look similar but describe very different terrain. The second is forgetting that contours never cross, except at overhangs, which are rare on hiking maps. The third is reading only the route line and ignoring the ground beside it — a path that looks easy on the map may cross a steep side slope just off the trail. Read the whole area around your route, not just the line itself.