Ask anyone this question: what is the highest mountain in the world?
Almost everyone gives the same answer. Everest. 8,849 meters. Children learn it at school, and adults still remember it thirty years later, when they have forgotten everything else from that room.
The answer is right. It is also wrong.
Everything turns on one small thing: where you begin to measure.
We measure mountains from the sea. Not from the sea near the mountain — from the level of all the sea in the world, which is more or less the same everywhere. So when we say that Everest is 8,849 meters high, we mean this: begin at the sea, climb to the top, and you have gone up 8,849 meters.
That is a good rule. It is also only a rule, and we chose it. Choose a different one, and a different mountain wins.
There is a mountain in Hawaii called Mauna Kea. Above the sea it is 4,207 meters — less than half of Everest. No book of great mountains has room for it.
But Mauna Kea does not begin at the sea. It begins on the floor of the sea, deep in the dark, and it climbs from there. From its foot to its top, Mauna Kea is about 10,210 meters.
That is 1,300 meters more than Everest.
Mauna Kea is the higher mountain. It has always been the higher mountain. We simply cannot see most of it, because 6,000 meters of it stand under water.
The second mountain is stranger.
The world is not quite round. It turns, and because it turns, it is a little wider through the middle than it is the other way. Every country near that middle line sits further out than the rest of us.
Chimborazo is a mountain in Ecuador, very close to that line. Above the sea it is only 6,263 meters, and Everest beats it easily.
But measure from the middle of the world, and everything changes. The top of Chimborazo is about 2,072 meters further from the middle of the world than the top of Everest. Nothing on Earth is further out. If you stand up there, you are standing at the one place on this world that is nearest to the moon, and to space, and to everything else out there.
So which mountain is the highest?
All three answers are true. Everest is the highest above the sea. Mauna Kea is the highest from its own foot. Chimborazo is the furthest from the middle of the world. No one is lying to you. The three mountains are answering three different questions, and school only ever asks one of them.
There is a reason it asks that one.
Sea level is the rule that matters for a human body. There is less and less air as you climb away from the sea, and near the top of Everest so little of it is left that a strong person can die up there in a few hours. Mauna Kea never asks that of you. Most of it stands under water, and there is a road up much of the rest — there are people who work on the top of it, and they drive home in the evening.
Everest is not the highest mountain in the world. Everest is only the highest mountain above the sea.
But the sea is where we live, and where we begin, and so the sea is what we measure from. We chose the question. Everest simply gave us the hardest answer to it.