Lighting and electronics

Breadcrumb navigation

Also called breadcrumb trail, track line

What is breadcrumb navigation?

Breadcrumb navigation draws your loaded route as a line on a blank screen with an arrow for your position, without any underlying map. It tells you whether you're on the route, and nothing about what's around you.

Shows: Your track as a line
Does not show: Any map underneath
Good for: Following a known route

How it works without a map

The cheapest way to give a watch navigation is to skip the map entirely. Draw the loaded track as a line, put a triangle on it for where you are, and let the user match one to the other. That's breadcrumb navigation, and it's what most mid-range GPS watches offer.

Why it is enough most of the time

For following a route you already know exists, it works surprisingly well. You can see when you've drifted off the line, and off-course alerts on most watches will tell you within a hundred meters or so. It costs almost nothing in battery or storage compared to rendering real maps.

Where it stops being enough

Its limits appear the moment the plan changes. With no basemap there's no way to see the trail you're standing at the junction of, no way to find an alternative route, and no way to identify the drainage you'd have to descend if the weather turned. You can see that you're off route without being able to see anything about where you actually are.

That's the case for a watch with onboard maps, or at minimum for carrying a phone with offline maps as the tool you turn to when the breadcrumb stops being enough.

What this means when you're choosing

Whether the device has any basemap at all, or only the line
How it warns you off-route, since a line alone is easy to miss
A phone with real maps as the backup, because the line is not navigation

The common mistake

Relying on it when the plan changes

It tells you whether you are on the line and nothing about what surrounds it. The moment you need to bail, find water or take a different trail, a line on a blank screen is no help at all. Carry a real map for the terrain, on paper or on a phone.

Common questions

For following a known route on marked trail, yes. It falls short when you need to improvise, because without a basemap you can see that you're off route but nothing about what's around you.

Do I need a watch with full maps?

Not if you carry a phone with offline maps as your backup, which is what most hikers actually do. Onboard maps are worth paying for if you go off-trail or want the watch to work alone.

Where this comes up

Guides on Tom's Hiking where breadcrumb navigation changes which product is right for you.

More in lighting and electronics

Lumens

Lumens measure the total light a headlamp emits in all directions. It's the headline number on every box and it says nothing about where that light goes, so a 400 lumen lamp with a bad beam can be less useful than a 200 lumen one with a good one.

Beam distance

Beam distance is how far a headlamp usefully projects light, quoted in meters. The industry standard measures it to the point where illumination falls to 0.25 lux, roughly the brightness of a full moon, which is dimmer than most people picture.

Flood vs spot beam

A flood beam spreads light wide and close for camp tasks and slow ground. A spot beam concentrates it into a narrow cone that reaches further, for seeing ahead at speed. Most trail headlamps mix both, and the mix matters more than the lumen count.

Regulated output

A regulated headlamp holds a steady brightness as its battery drains, then drops off sharply near the end. An unregulated one fades continuously from the moment you switch it on, so it's dim long before the battery is actually empty.

Reactive lighting

Reactive lighting uses a sensor to measure reflected light and adjusts brightness automatically, dimming when you look at a map and brightening when you look down the trail. It extends battery life and can feel unpredictable at speed.

Red light mode

Red light mode is a dim red setting on a headlamp that lets you see nearby things without spoiling your night vision. Your eyes take 20 to 40 minutes to adapt fully to the dark, and white light undoes that in seconds, while dim red light barely disturbs it.

IP rating

An IP rating states how well a device resists solids and water, under the IEC 60529 standard. The first digit covers dust and the second water, so IPX4 is splash resistant, IPX7 survives brief submersion, and IP67 does both.

Watt-hours (Wh)

Watt-hours measure how much energy a battery stores: voltage multiplied by capacity in amp-hours. Unlike mAh, which is quoted at the cell's own voltage, watt-hours let you compare any two batteries fairly, and they are the unit airlines use to set carry-on limits.

GPX file

A GPX file is the standard open format for storing GPS routes, tracks and waypoints as plain text. It's what you download from a trail site and load onto a watch or phone, and almost every mapping app and GPS device reads it.

ABC sensor

ABC stands for altimeter, barometer and compass, the three sensors in an outdoor watch. The altimeter and barometer are the same pressure sensor read two ways, and the compass is a magnetometer that gives you a heading when you're standing still.

Exit pupil

Exit pupil is the width of the beam of light a binocular sends to your eye, found by dividing the objective lens size by the magnification. An 8x25 has a 3.1mm exit pupil and an 8x32 has 4mm; the bigger number looks brighter in dim light.

Eye relief

Eye relief is how far behind a binocular's eyepiece your eye can sit and still see the whole field of view, measured in millimeters. Glasses hold your eye farther back, so hikers who wear them need about 15mm or more to avoid a view ringed in black.

ED glass

ED glass, short for extra-low dispersion, is lens glass that bends red, green and blue light by nearly the same amount. In binoculars it cuts the purple and green fringes around dark edges against a bright sky, so the image looks sharper and truer in color.

By Tom · Last reviewed August 13, 2026. Back to the glossary

Breadcrumb navigation

What is breadcrumb navigation?