Topographic isolation

The topographic isolation of a summit is the minimum horizontal distance to a point of equal elevation, representing a radius of dominance in which the peak is the highest point. It can be calculated for small hills and islands, major mountain peaks, and even submarine summits. Mount Everest, the highest point on Earth, has an undefined isolation, since there is no higher point to reference.

Because topographic isolation can be difficult to determine, a common approximation is the distance to a peak called the nearest higher neighbour (NHN).