The Tallest Mountain in the World May Not Be What You Think

It’s all depends on whether you measure from sea level, sea floor, or even the planet’s center.

the mountains around Pokhara, blanketed by fog

Nepal’s Annapurna Range boasts a number of stunning mountain peaks.

Photo by Susan Portnoy

As dawn’s twilight settled over Pokhara, I pointed toward the large shadow towering over the city’s thousands of tiny shimmering lights and asked for the mountain’s name. “That’s not a mountain; it’s a hill,” said Rabina, my Nepali guide, of the 8,500-foot Odane Hill. “Seriously?” I asked. To earn the moniker, says Rakesh Shahi, owner of Mystik Mountains Adventures in Kathmandu, the summit must have snow cover year-round and that happens roughly above 18,000 feet. I had to admit, it made sense; the colossal silhouette of Annapurna South’s snowcapped summit, at almost 24,000 feet, dwarfed Odane. Even so, Annapurna is smaller than Everest, which is considered the world’s tallest mountain. Or is it? The answer depends on your perspective.

How are mountains measured?

If you measure from sea level, says Lynn Moorman, professor of Earth and Environmental Sciences at Mount Royal University in Calgary, Everest is hands down the winner at 29,032 feet and steadily rising. The Indian and Eurasian plates forming the Himalayas continue to collide, says Moorman, lifting the continental land, albeit slowly. “They [tectonic plates] move about the speed of your fingernails growing.” But while Everest’s height increases, it’s simultaneously being worn away by the elements, earthquakes, and avalanches.

By adopting a different measurement approach, the United States could lay claim to the world’s tallest mountain. Mauna Kea, a dormant volcano on the island of Hawai’i, rises 13,796 feet above sea level. However, if you take into account the 19,700 feet the volcano extends to the sea floor, Mauna Kea is a whopping 33,500 feet in total and significantly taller than Everest.

Or, with yet another kind of measurement, South America would be home to the highest mountain in the world. If you compute the distance from the planet’s center, Chimborazo, located near the equator at 20,564 feet in Ecuador, earns the top honor. That’s because the earth is more like an ellipsoid than a perfect sphere. Imagine gently squeezing a small, soft ball at its north and south poles; the ball will bulge east to west, at its “equator,” so to speak. “The distance from one point on the equator to the exact opposite point is going to be longer than from the north pole to the south pole,” Moorman explains. “So if you’re just looking at that, then that one [Chimborazo] would be farthest from the earth’s center” and taller than Everest.

How was Everest measured?

Of course, the tools used for measurement have changed over the decades, which in turn have affected official heights. Using trigonometrical calculations, the Survey of India measured Peak (XV), later named after Sir George Everest, the former Surveyor General of India, at 29,002 feet during the 19th century. However, in 1954, another India survey added 26 feet. The most recent measurements of Everest by Nepal in 2019 and by China in 2020 added another four feet to the mountain’s height, raising the grand total to approximately 29,032 feet, the mountain’s current “official” height.

On a related note, the Appalachians, which formed between 300 and 500 million years ago, may have been as tall or taller as Everest at one point. The 2000-mile range, extending from Canada to Alabama, has had eons more time for the forces of nature to chip away at its stature. Who knows, in 100 million years, Everest may be nothing more than a hill.

Susan Portnoy is a freelance photographer, travel writer, based in New York City. Her work has appeared in publications such as Travel + Leisure, Smithsonian, Fodor’s, Newsweek, and Hemispheres.
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