Measuring mountains might not seem overly complicated, but there actually are several ways in which it can be done. Depending on which technique is used, the title of world's tallest mountain could go to any of several mountains in various regions of the world. Some scientists also heatedly debate the issue, arguing that their technique is the most accurate, conventional or widely accepted method. The world's tallest mountain differs depending on whether a mountain's height is measured from sea level, by vertical rise, from the base or even from the center of the Earth.
Measured from Sea Level
When most people think about the elevation of a mountain, they often visualize elevation from sea level, which also is one of the most widely accepted measuring techniques used when determining the world's highest mountain. People are familiar with sea level measurements because elevation is classically expressed as a distance from sea level on road signs, maps and textbooks. This also is an easy form of measurement to visualize. When measuring from sea level, Mount Everest is the uncontested world's tallest mountain, with a peak that is 29,035 feet (8,850 m) above sea level.
Measured from the Surrounding Terrain
Mount Everest has an advantage because it is situated on a high plateau, and the plateau's elevation above sea level is included in the height of the mountain when measured using this method. For people who are more interested in vertical rise from the surrounding terrain to the top of the mountain, Mount McKinley would be considered the tallest mountain. Although its maximum elevation above sea level is lower than that of Mount Everest, Mount McKinley's vertical rise is about 18,000 feet (5,500 m), compared with Mount Everest's rise of about 12,000 feet (3,700 m).
Measured from Its Base
Some people prefer to measure mountains from their base, no matter whether the base is above sea level. Measuring from its base at the bottom of the Pacific Ocean, Mauna Kea likley is the world's tallest mountain, with a distance from the ocean floor to the top of the mountain being 33,476 feet (10,203 m). This beats out Mount Everest even though Mauna Kea's elevation is only 13,796 feet (4,205 m) at its peak.
Another contender using this method of measurement is Mount Lamlam, whose base is deep in the Marianas Trench, which is in the western part of the Pacific Ocean. There are differing reports of Mount Lamlam's measurement from base to top. The most extreme claims state that it is 37,820 feet (11,527 m) high, which would make Mount Lamlam higher than Mauna Kea and therefore the world's tallest mountain using this method of measurement.
Measured from the Center of the Earth
For people who prefer to measure from the center of the Earth, the world's tallest mountain is Chimborazo, which is 3,968 miles (6,384 km) from the center of the Earth at its peak, although its elevation is only 20,565 feet (6,268 m) above sea level. It is located in Ecuador, near the Earth's Equator, which gives it an advantage using this method of measurement, because the Earth bulges slightly in the middle. This means that the Earth's surface is farther away from its center near the Equator than in other places.