Four Different Mountains Are the Tallest on Earth

What’s the highest point on our planet?

This bit of trivia is likely known by many humans, not just fans of mountains. If you went into Final Jeopardy! with the lead, you would confidently scrawl “What is Mount Everest?” on your lectern and toast yourself to becoming a champion.

Everest – also known as Sagarmatha or Qomolangma – reaches 29,031 feet (8,849 meters) above sea level. The world’s most famous crag is nearly 800 feet higher than second place, K2.

Done and dusted.

Everest is the tallest mountain on Earth.

Right?

Unfortunately, the situation isn’t quite so easily concluded. And, by the end of this article, you still might not find a satisfactory answer. Nonetheless, let’s press onward!

No other peak has a number higher than 29,000 feet in front of its elevation. How is this topic not clear-cut, then? Some of our favorite culprits emerge to make this a rocky matter: perspective, oceans, and mathematics.

Let’s start with a piece that we often overlook, thanks to convention. Everest rises 29,031 feet above sea level. We often think about the elevation figures but discount the “sea level” part. What is sea level? Once again, on the face, seems to be a straightforward question.

It’s the point where oceans meet land!

Since humans have become cartographers and geographers, we’ve used this point as our basis for measuring elevation. It makes a good amount of sense; disregarding a swim, sea level would be the point where you could start a hike and climb the entire elevation of a hill, mountain, or any higher point. Indeed, in 1990, a team spent three months walking from the Bay of Bengal to the top of Everest. The first measurements of the world’s highest mountain, undertaken by the Great Trigonometrical Survey, led at one point by a man named George Everest, began at the sea in India in 1802. From sea level, they led a tedious, precise march to the north; it took the team three decades to reach the foothills of the Himalayas! Not until the early 1850s did the Survey navigate the political and topographic headaches to reach a suitable approximation of Everest’s height. Still, this stature came directly from comparing heights relative to the relatively local sea level.

So, sea level is where the ocean meets the land and it’s an intuitive base by which we can measure elevation. With enough effort, we can triangulate any height, even from distant oceans.

You might next ask an important question: is the sea level the same at all global points? Does Everest rise 29,000 feet above the Bay of Bengal and the point where the Atlantic Ocean touches Long Island, for instance?

We might reasonably deduce the answer is yes. After all, the oceans are not multiple independent bodies but one giant bathtub. If you created a miniature mountain chain or continent as an island in your tub and filled water around the central body, the points where water meets land would all be at zero, or sea level. It would make sense if Earth worked this way, as well.

But that’s not how it plays out.

The scenario in the bathtub works because the surface – the bottom of the tub – is uniform and, because it’s small enough, under the same amount of pull from gravity at all points. The Earth’s surface is not a perfect sphere and the effect of gravity is not – somewhat counterintuitively – the same at all places. These deviations from a perfect Earth spheroid occur for two reasons: spin and density.

Let’s start with the former. If the surface of our planet were smooth and it did not spin, we might inhabit a perfect sphere. Instead, because the planet spins, centrifugal force along the axis creates an equatorial bulge. Measured from the core, the diameter of Earth is larger at the equator than it is at the poles by about 27 miles! Mathematicians call this shape an oblate spheroid.

Further complicating the situation is the density of matter on Earth, namely that it is not the same in all spots. Magma distributions vary, as do the geological makeup of the crust. Where matter is densest, gravity is highest.

Combine oblation and gravity discrepancies and we get a planet covered in oceans that are not all the same height relative to the core. Where gravity is higher, water is pulled more strongly toward that region; in areas of lower gravity, water would not be pulled as strongly and might be imagined to “bulge.” The result is a sea level that is anything but level. A spot in the Indian Ocean sits about 350 feet below the average sea level, thanks to gravitational anomalies!

So, our notion of height seems to be based on a standard that is, well, not standard. Everest might be 29,000 feet above its local sea level, but how high would it be if we transported it to the middle of Kansas? Maybe the difference between local sea levels would be slight, but it wouldn’t be zero. Do we just have to toss out the sea level altogether?

“Nay, stay the execution on sea level, we have the geoid,” say the mathematicians!

What would the sea level be beneath Everest? The Great Trigonometric Survey mapped the mountain from the distant bay, but if we could cut a tunnel to the base of Everest, would that sea level be the same distance from the core or the same height? How might we understand sea level when nearly five miles of rock sit atop such a spot?

Enter the geoid.

First described by the great mathematician Johann Carl Friedrich Gauss, the geoid is an imaginary, undulating shape whose surface would be ocean, based on Earth’s particular shape, spin, and gravity (minus the influence of tide and wind). In other words, it’s where water would be, based on a locality’s gravity and its spot on the oblate spheroid. In a way, we have already encountered the geoid in action, as Earth’s oceans adhere to it. However, the geoid does not stop at oceans; it extends over continents, too. Technically, the geoid is the shape in which gravity is perpendicular to every point; the geoid is an equipotential surface. The geoid is the place where water would be if nothing were on top of the spot; the geoid can, therefore, define “sea level.” Extending this concept to land, however, takes imagination to visualize. Though it was theorized in the past, we did not know the precise proportions of the geoid until satellites allowed us to make accurate measurements of gravity on small scales in the 1990s.

This idea allows us to extend the concept of sea level to every point on the planet, even those covered by five miles of rock.

Above the geoid, Mount Everest is indisputably the tallest point on the planet.

But the story does not end here. Is Everest the highest point on the planet?

Let’s revisit Earth’s oblation and equatorial bulge. Because the planet spins, it’s fatter in the middle, relative to the core. Since Everest is the tallest above sea level/the geoid, is it also the farthest point from the planet’s core?

In general, the closer one is to the equator, the farther one is from the core.

Meet Chimborazo. At 20,549 feet (6,263 meters) above sea level, it is the highest point on Earth.

This volcano is nearly 8,500 feet (more than a mile) shorter than Everest, but it’s the highest point on Earth. How does that work?

It’s the bulge.

Chimborazo is in Ecuador, just one degree south of the equator. By contrast, Everest almost touches the 28th parallel. Amazingly, the top of Chimborazo sits 1.3 miles farther from the center of the planet than does Everest’s apex!

This fact isn’t some technicality. If you stood on the Moon, the closest point on Earth to you would be Chimborazo, not Everest. One could, therefore, define Chimborazo as the highest point on Earth.

If you find this scenario difficult to visualize, think of two people of different heights. You are six inches taller than your sibling. When you stand next to each other, you are clearly six inches higher. Now, send your sibling to the second floor of a building. Who is taller? From toe to head, you are still six inches taller, but your sibling is now higher than you. Because of the equatorial bulge, Chimborazo reaches farther into space than Everest. Above the geoid, however, Chimborazo only elevates 20,549 feet. Not only does the land bulge but so do the ocean and the geoid. Everything starts higher near the equator.

Why is Chimborazo not universally known as the highest point on the planet, then? That’s a great question. Partially because of convention (i.e. we’ve always used sea level) and partially because sea level still matters. If you could dig up the entirety of Everest and then Chimborazo and switch the rocks, Everest would still rise 29,000 feet above the geoid in Ecuador. So, Everest is taller, and this distinction is, again, not just a technicality. Real attributes come along with the distance above sea level. For example, the higher above sea level one rises, the less oxygen the atmosphere contains. Just like the ground and the sea level, the atmosphere also rises near the equator. The planet’s atmosphere bulges! So, even though Everest is lower from the viewpoint of space, it has less oxygen than Chimborazo because it rises more above sea level.

Confused yet? Let’s add some more wrinkles.

We’ve defined the geoid/sea level as the base of note. But does it need to be? Couldn’t the distance between the core and the apex of a mountain be just as important as the sea level? If the atmospheric differences did not exist, I would argue the highest point from a vantage point in space should garner the crown, but the reality is cloudier. Still, if you walked from the ocean in Ecuador to the top of Chimborazo, you would not ascend as many feet as you would from the ocean in India to the top of Everest.

What if we discard the notions of core and sea level completely and just look at the mountains? Would Everest still be the tallest?

As it turns out, the answer is, again, no. Just like the equatorial bulge, which lifts everything upward near the equator, not all mountain bases are constructed equally. Ground level varies wildly. For example, the central parts of the United States, widely considered to be flat expanses, have a higher elevation than many parts of the Appalachian Mountains. Yet, if one looked at the mountains of the east, one would see crags that rise much higher from their bases than anything in Nebraska, for example. Nebraska’s Panorama Point is higher than both New York’s Mount Marcy and Maine’s Katahdin, both beastly crags that dominate the horizon. The reason for this oddity is tectonic; the region in the Midwest and West has been uplifted by the goings-on of the Earth’s innards.

Everest belongs to the Tibetan Plateau, a massive block that has been uplifted. What constitutes a base is poorly defined and often arbitrary, but Everest’s base begins somewhere in the range of 15,500 feet. To get to the summit, one must scale nearly 14,000 feet of some of the world’s gnarliest terrain, but this rise does not top the list.

From base to summit, the tallest mountain in the world is Denali.

To climb North America’s highest peak, one begins around 2,000 feet above sea level and ascends to 20,310 feet (6,190 meters). The gain of more than 18,000 feet is more than any other peak on the planet.

So, by some definition, Denali is the tallest mountain on Earth. If you sawed Everest off at its base and placed it next to Denali, the Alaskan would stand over its Asian cousin.

We still have not finished the debate, however.

So far, we have dismissed anything that happens below sea level. Lurking in the depths is a mountain that stakes a claim to the crown.

Looking at Hawaii’s High Point, Mauna Kea, might leave you a bit unimpressed. It lacks the grandiosity and jaggedness of Everest and Denali. At 13,803 feet (4,207 meters) above sea level, it pales in comparison to Everest. Its entire height above sea level is 5,000 feet less than Denali’s rise over its base.

But these numbers are deceiving. Mauna Kea’s base is not the sea level. Mauna Kea comes directly from the bottom of the ocean. From the Pacific floor, Mauna Kea climbs an astonishing 33,474 feet (10,203 meters)! One could argue this is pure verticality. A mountain cannot start lower than the ocean floor. Certainly, specific spots on the ocean bed will be lower than others, but at each point on Earth, the highest a peak could theoretically rise would be from the bottom of the ocean. This above-base mark crushes both Denali and Everest, but, since we’re terrestrial creatures, we never see the majority of the volcano.

Four mountains have legitimate claims to being the tallest on Earth.

To recap:

Tallest above sea level: Everest

Tallest above core: Chimborazo

Tallest above base on land: Denali

Tallest above base on ocean floor: Mauna Kea

Which definition makes the most sense to you? Though I absolutely love Everest, part of the geoid argument sticks in a recess of my brain, seeming to make little sense. Seeing Chimborazo from space would make it a surefire “highest” in my book, but scientists and geographers continue to stick with Everest. Part of the issue stems from the fact that “tallest” and “highest” don’t have to be the same thing. Further, though I can see how Mauna Kea is the tallest from its base from a strict definition, as a human, one would have to climb more on Denali.

Each contender merits the title in its own way, which just goes to show the things we might take as absolute aren’t necessarily the case on a cosmic scale.

BONUS FACT:

Chimborazo is close to the equator, but other mountains are even closer. The crag farthest from Earth’s axis (i.e. where it spins) is Cayambe, also in Ecuador, at just 1 minute 30 seconds north. On a spinning spheroid, the point farthest from the axis spins the fastest. Therefore, if you stood on Cayambe’s pinnacle, you would be spinning faster than any human on the planet!