What is a Pinnacle Point?

A pinnacle point is a point from which no higher point can be seen. In other words, if you were standing at a pinnacle point, you could face any direction and every point you could see would have a lower elevation than where you are standing. My algorithm to find pinnacle points takes the curvature of the earth, the bending of light from atmospheric refraction, and local topography into account. For more information on the algorithm, refer to the info section of the interactive map. The resolution of the human eye and obscuration from clouds and fog are not considered. If light can travel from one point to another unobstructed under ideal atmospheric conditions, then the points are considered to be in view of each other.

Only the yellow mountains are pinnacle points. The left side shows a chain of taller mountains terminating at a pinnacle point in the middle. The right side shows another pinnacle point that would be disqualified if not for the smaller mountain obstructing its view.

How far you can see varies greatly from place to place. The average person’s horizon is just under 5 km away if standing on level terrain, while the farthest two points on Earth’s surface that can see each other are 538 km apart. This impressive record is held by Mt. Dankova in Kyrgyzstan and Hindu Tagh in China, with the Tarim Basin between them.

*The farthest two points on earth that can see each other, 538 km apart.*

These distant mountains can only see each other because light bends as it travels through the atmosphere. The varying pressures and temperatures in the atmosphere cause light to refract in an arch, gently bending towards the Earth at low elevations. This allows light to arch over land that would otherwise obstruct the target. In other words, the bending of light in the atmosphere lets you see farther than you would otherwise be able to.

*Atmospheric refraction bending light over the Tarim Basin, allowing Mt. Dankova in Kyrgyzstan to see Hindu Tagh in China from 538 km apart.*

Not all notable high points are pinnacle points. The higher you are the farther you can see after all, revealing an expanded area where another even higher point could be lurking. There are chains of peaks where each can see a higher peak off in the distance, until the chain eventually ends at a pinnacle point. Iceland, for example, only has one pinnacle point, unless there are some with under 300 m of prominence that my algorithm would not have found. This isoated landmass having only one pinnacle point means that no matter where you are in Iceland, if you climb to the highest point you can see, and repeat, you’ll eventually end up at the highest point of the island.