What’s the world’s tallest mountain? Here's why some feel the title should be reconsidered

The world’s highest peaks are deeply revered around the world, likely due to the immense difficulty of reaching them.

In 2019, Nirmal ‘Nims’ Purja gained national attention by climbing 14 of the world’s tallest mountains in a little over six months. Each of these mountains are so tall that oxygen levels at the peak are not sustainable for human life, according to National Geographic.

But not everyone agrees on which mountain is the tallest. Here’s why some people don’t consider Mount Everest to be the tallest mountain in the world.

What is the tallest mountain in the world?

Located in the Himalayas between Nepal and Tibet, Mount Everest is the mountain that reaches the highest elevation above sea level, according to History.com. While most people consider Mount Everest to be the world’s tallest mountain, competing definitions of “tallest” have added other mountains to the conversation.

According to the National Park Service, Mount Everest’s base is 14,000 feet above sea level, meaning it is a little over 15,000 feet from base to peak.

Mauna Kea, a shield volcano in Hawaii, is technically the world's tallest mountain from base to peak. However, its underwater base is far below sea level, so it doesn’t reach the elevation that Mount Everest does, according to the National Ocean Service. A mountain’s distance above sea level is the most common measurement for its height, but Mauna Kea could be considered the tallest by those who want to argue the technicality.

If the underwater portion of Mauna Kea disqualifies it from the competition, then Alaska’s Denali, formerly known as Mount McKinley, becomes the world’s tallest mountain from base to peak, according to Montana State University. Unlike Mauna Kea, the base of Denali is situated on land. Its base is situated at an elevation of 2,000 feet, and its summit is only about 9,000 feet below Everest’s, according to the National Park Service. This makes Denali roughly 3,000 feet taller than Everest, when measured from base to peak.

Ecuador's Mount Chimborazo could also be in the running for tallest mountain, as its peak is farther from the center of the Earth than any other, according to the National Ocean Service. This extra distance is a result of the fact that Earth is not perfectly round. Instead, it is oblong with a “centrifugal bulge,” causing Mount Chimborazo’s peak to be over 6,800 feet further from the center of the Earth than Everest’s, despite the fact that Mount Everest actually reaches an elevation 9,000 feet higher.

How tall is Mount Everest?

Mount Everest is 29,031.69 feet tall, according to National Geographic. BBC reports it grows a few millimeters taller each year as the continental plates under it continue to collide.