First, a definition of terms. The highest place on Earth is the one that’s the most distant from the center of the Earth.
And so, the highest point on the Earth is Mt. Chimborazo in Ecuador in the Andes mountain chain. It’s about 2.4 kilometers higher than Mt. Everest (and you thought Mount Everest was going to be the answer).
Here’s why. The Earth isn’t a perfect sphere; it’s somewhat like a flattened ball with the widest part being slightly south of the Equator. Measured from pole to pole, the Earth is 12,712 km across. But if you measure the diameter of Earth at the equator, you get 12,756 km across. Do the math, that means regions at the equator are 22 km further from the center of the Earth than the poles. And this is on average, specific points can get even higher.
What this means is that if you were standing at the widest part of the bulge, you would be closer to outer space than if you were standing at the poles. Mt. Chimborazo sits at about the highest point in this bulge, giving it an extra 21 kilometers over Mt. Everest. I would like to give Mt. Everest its due by saying it is the highest place on Earth above sea level, but it isn’t the tallest mountain in the world.
The biggest mountain in the world is Mauna Kea at 10,206 meters from base to summit; bearing in mind that its base is several thousand meters below sea level. We only see the top 4000 meters.