highest mountain:

It is very unlikely that all given heights are correct to the nearest metre; indeed, the sea level is often problematic to define when a mountain is remote from the sea. Different sources often differ by many metres, and the heights given below may well differ from those elsewhere in this encyclopedia. As an extreme example, Ulugh Muztagh on the north Tibetan Plateau is often listed as 7,723-7,754 m, but appears to be only 6,973-6,987 m. Some mountains differ by >100 m on different maps, while even very thorough current measurements of Mount Everest range from 8,844 to 8,850 m. These discrepancies serve to emphasise the uncertainties in the listed heights.

Though some parts of the world, especially the most mountainous parts, have never been thoroughly mapped, it is unlikely that any mountains this high have been overlooked, because synthetic aperture radar can and has been used to measure altitudes of most otherwise inaccessible places. Still, heights and/or prominences may be revised, so that the order of the list may change and even "new" mountains could enter the list over time. To be safe, the list has been extended to include all 7,200 m+ peaks.

The highest mountain is not necessarily the tallest, considering the difference in height between the peak and the surrounding base of the mountain. There is no precise definition of surrounding base, but Mount McKinley, Mount Kilimanjaro and Nanga Parbat are possible candidates for the tallest mountain on land by this measure. The bases of mountain islands are below sea level, and given this consideration Mauna Kea is the world's tallest mountain, rising about 10,200 meters (33,500 feet) from the Pacific floor.

The highest mountains are not necessarily those farthest from the center of the Earth, because the figure of the Earth is not spherical. Sea level closer to the equator is several miles farther from the center of the Earth.