We can get complacent when using GPS for city navigation, because the turn by turn directions are usually close to perfect. But in the backcountry, when your GPS only tells you distance and straight line bearing from one point to another, you often need to add some common sense and basic map reading. Let's look at an example.

You're camped at Lower Hopkins Lake and want to go to the unnamed lake. Using the Gaia GPS app on your phone (my favorite choice), you add a waypoint at the unnamed lake, and then use the “Guide Me” function to get distance and bearing from your current position.

• Your phone tells you it’s about 2 miles and a bearing of 250 degrees from your camp to the lake.

• Would it be a good idea to follow this bearing ? Why or why not?

A GPS bearing shows only the straight line distance and bearing between two points. It doesn't show what's necessarily a good route choice. Following a direct bearing of 260 degrees would get you into some steep terrain, shown by the contour lines on the hillside that are very close together.

A longer, but probably better route is the green line. It's less steep, which is shown on the map by contour lines that are a bit farther apart.

Do you need a printed map, or necessarily a compass, to get to the lake? Probably not. But the basic skills of reading contours can still come in handy, and even if a GPS device is the only navigation tool you carry. Following a direct line, especially in the mountains, is rarely the best choice.

Map by CalTopo, the best backcountry mapping software.

Want to learn the basics of how contour lines show real world terrain? Check out the video below.