What is mountain prominence?

Prominence is how far a summit rises above the lowest point you'd have to descend to on the way to any higher summit. That lowest point is called the key col or key saddle. A peak with high prominence stands on its own; a peak with low prominence is a bump on a bigger mountain's ridge, however high it is above sea level.

The definition, with a picture in your head

Stand on a summit and imagine walking toward the nearest higher mountain, staying as high as you can. You'll have to come down somewhere, usually to a saddle on a connecting ridge, before you can climb again. The lowest point on the best possible route is the key col. Prominence is the height of your summit minus the height of that col.

Another way to picture it: flood the world until your peak becomes the highest point of its own island. Prominence is how far the summit sticks up above that sea.

Examples that show why it matters

Everest's South Summit is the clearest case. It's taller than every mountain on Earth except Everest itself, yet nobody counts it as a separate mountain, because you only drop a few meters from it before the ridge climbs to the main summit. Elevation says it's the second-highest summit in the world. Prominence says it isn't really a summit of its own.

The app's own database shows the same thing at scale. It contains 27 summits above 8,000 m, but there are only 14 recognized eight-thousanders. The rest are subsidiary tops on the same massifs, like Kangchenjunga's south and central summits.

How peak lists use prominence

Because subsidiary tops are everywhere, peakbagging lists need a rule for what counts as a separate summit, and prominence is the usual tool:

• Colorado's fourteeners conventionally count a summit as ranked if it rises at least 300 ft above its saddle with a higher neighbor.
• The Marilyns in Britain and Ireland are every hill with at least 150 m of prominence, regardless of height.
• Ultras are summits with 1,500 m or more. There are about 1,500 worldwide (see the list of ultra-prominent peaks).

Some famous lists don't use prominence at all. The Munros, for instance, are decided by the Scottish Mountaineering Club's judgment rather than a fixed drop. Our peak bagging guide covers how to pick a list.

Prominence and what you can see

Prominent peaks are the ones that dominate a view, because they rise well above the ridges around them. That's part of why they're easy to spot from a long way off, though distance and the curve of the Earth also play a part; see how far away you can see a mountain. It's also why prominence often decides the mountain-versus-hill argument better than raw height does.

Why prominence data is patchy

Prominence has to be calculated from elevation data across a whole region, since finding the key col can mean tracing ridges for hundreds of kilometers. Most maps don't record it. In OpenStreetMap, the source of the app's peak database, only 8,840 of 687,599 summits (1.3%) carry a prominence value, and those were added by hand from other sources. A summit without one isn't minor; nobody has tagged it yet.

Where you'll see it in Mountain Identifier: Peaks

When a peak you log has a prominence value in OpenStreetMap, the app shows it on the peak's page next to its elevation. Because the tag is missing for most summits, the app doesn't rank peaks by prominence. Its "rarity" label is based on elevation alone. Logging peaks by hand is free; identifying them with the live view or a photo is part of Pro.

Frequently asked questions