The question of the “biggest mountain ever” is complex, as the answer depends entirely on the method of measurement used. A mountain considered the “highest” point above sea level is different from the one that is the “tallest” from base to peak, and both are distinct from the one with the greatest physical bulk. This ambiguity highlights the diverse ways geological structures can be compared. Several mountains hold a claim to the title, each for a specific, measurable reason.
Measuring Height Above Sea Level
The conventional and most widely recognized definition of a mountain’s height is its elevation above mean sea level. Under this standard, the undisputed titleholder is Mount Everest, situated in the Mahalangur Himal sub-range of the Himalayas. Its summit marks part of the border between Nepal and the Tibet Autonomous Region of China. The official, jointly agreed-upon height is 8,848.86 meters (29,031.7 feet) above sea level, a measurement announced in 2020 by Chinese and Nepali authorities.
The height of this mountain is a direct result of powerful tectonic forces. Everest’s formation began tens of millions of years ago with the collision of the Indian-Australian Plate and the Eurasian Plate. This ongoing geological process causes the continental crust to crumple and thicken, relentlessly pushing the Himalayan range upward.
Measuring Height from Base to Peak
A different perspective focuses on the total vertical distance from the mountain’s structural base to its summit, regardless of whether the base lies above or below the ocean surface. When measured this way, the Hawaiian volcano Mauna Kea surpasses Mount Everest by a substantial margin. Mauna Kea is a dormant shield volcano on the island of Hawaiʻi, rising from the floor of the Pacific Ocean.
The mountain’s summit reaches an elevation of 4,207 meters (13,803 feet) above sea level, less than half the elevation of Everest. However, its base extends approximately 6,000 meters (19,700 feet) below the sea surface to the deep ocean floor. The total height of Mauna Kea, measured from its base in the Hawaiian Trough to its peak, is approximately 10,210 meters (33,500 feet). This makes it the world’s tallest mountain by this metric.
Mountains of the Largest Mass and Volume
Shifting the definition of “biggest” to encompass physical bulk, mass, and area coverage reveals yet another contender: Mauna Loa. Located on the same island as Mauna Kea, Mauna Loa is the largest active volcano on Earth by both mass and volume. The mountain’s name, meaning “Long Mountain” in Hawaiian, is fitting for its enormous footprint.
Mauna Loa is a massive shield volcano characterized by highly fluid lava flows. The volcano covers about 51% of the island of Hawaiʻi and spans a maximum width of 120 kilometers (75 miles). Its estimated volume of solid rock is approximately 75,000 cubic kilometers (18,000 cubic miles), a bulk so immense that the ocean floor actually bends under its weight.
The Biggest Mountain Beyond Earth
To fully address the question of the biggest mountain “ever,” one must look beyond Earth’s geological constraints to the solar system. Olympus Mons, a massive shield volcano on Mars, holds the record for the largest mountain known. Its colossal size is a result of Mars’ lower gravity and the absence of mobile tectonic plates, which allowed lava to accumulate in one spot for billions of years.
Olympus Mons towers approximately 22 kilometers (14 miles) above the surrounding Martian plains, about two and a half times the height of Mount Everest above sea level. Its diameter stretches about 600 kilometers (370 miles), covering an area roughly the size of Arizona or Italy. Its enormous volume is estimated to be about a hundred times greater than that of Earth’s largest volcano, Mauna Loa, placing it in a category unmatched on our world.