What are contour lines? They’re the squiggly lines on your map that show elevation. Each line represents a specific height above sea level. How to read them: Close together = steep terrain Far apart = gentle slopes Circles = hills or mountains (the smaller the circle, the higher the peak!) Why it matters: Plan routes that match your fitness level Spot challenging climbs before you set off Find scenic viewpoints and avoid unexpected steep descents Pro tip: Combine contour reading with OS Maps’ 3D