A Matter of Measurement
For generations, schoolchildren have learned that Mount Everest in Nepal is the tallest mountain on Earth. That statement, however, depends entirely on how one defines "tallest." As BBC Science Focus explains, the question is not as straightforward as it seems, and there are actually three serious contenders for the title, each claiming a different record.
Everest: Highest Above Sea Level
Mount Everest stands at 86 metres 69 feet) above sea level, making it Earth's highest mountain above the ocean. This is the measurement most commonly cited, and it is why Everest is often considered the world's tallest peak. It was first summited on May 29, 1953, by Sir Edmund Hillary and Sherpa Tenzing Norgay.
Mauna Kea: Tallest From Base to Summit
However, if one measures from the base of a mountain to its summit, the title goes to Mauna Kea in Hawaii, USA. Mauna Kea rises 10,205 metres (33,481 feet, or 25 kilometres) from its base on the ocean floor to its peak. Only 4,205 metres of this height is above sea level; the remaining roughly 6,000 metres is submerged beneath the Pacific Ocean. This makes Mauna Kea approximately 4 kilometres taller than Everest when measured in this way.
Mauna Kea, whose name translates to "White Mountain" because of its frequently snow-capped summit, is a long-dormant volcano that has been inactive for about 4,500 years. The United States Geological Survey (USGS) notes that Mauna Kea is "likely to erupt again," but because it is home to the largest astronomical observatory on Earth, the USGS adds that "sensitive astronomical telescopes would, as a by-product of their stargazing, detect minute ground tilts possibly foretelling a future eruption."
In February 2021, American adventurer Victor Vescovo and Hawaiian marine scientist Dr Clifford Kapono completed the first full ascent of Mauna Kea from its base to its summit. They used the two-person submersible Limiting Factor for the underwater leg, then rowed for over five hours to Big Island in a three-person outrigger canoe. Over the course of three days, they cycled, hiked, and skied to the summit, ultimately securing a Guinness World Record.
Mount Chimborazo: Closest to the Sun
A third contender, Mount Chimborazo in Ecuador, claims the title of the point on Earth's surface closest to the sun. This is because Earth is an oblate spheroid that bulges at the equator, so mountains near the equator are farther from the planet's centre than those at higher latitudes. Chimborazo, an inactive volcano in the Andes, has a peak measuring 6,310 metres above sea level and lies just one degree south of the equator, closer than any other mountain. Measured from the centre of the planet, Chimborazo could rightfully be considered the tallest mountain on Earth.
The Verdict
So, which is the tallest mountain? The answer depends on the yardstick. Everest is the highest above sea level. Mauna Kea is the tallest from base to summit. And Chimborazo is the closest to the sun. Each claim is valid within its own definition, making the question of Earth's tallest mountain a matter of perspective rather than a single, unambiguous answer.