“Mount Everest is the tallest mountain on Earth”

It's widely believed that Mount Everest is the tallest mountain on Earth, a notion rooted in how we typically measure mountain heights. For centuries, the standard scientific and popular method has been to calculate elevation from sea level. In the mid-19th century, the Great (Review) Trigonometrical Survey of India meticulously measured Himalayan peaks, and in 1852, Radhanath Sikdar, an Indian mathematician and surveyor, confirmed that what was then known as Peak XV (later named Mount Everest) had the greatest elevation above sea level. This groundbreaking discovery solidified Everest's reputation as the "highest" point on Earth, a fact that has been taught in schools and recognized globally ever since.

However, the definition of "tallest" can be interpreted differently, leading to a fascinating distinction. While Mount Everest indeed reaches an astounding 8,848.86 meters (29,031.7 feet) above sea level, making it the highest mountain, it is not the tallest when measured from its true base to its summit. That honor belongs to Mauna Kea in Hawaii, a dormant volcano whose vast majority lies hidden beneath the Pacific Ocean.

From its base on the ocean floor, Mauna Kea rises approximately 10,210 meters (33,500 feet) to its peak, making it significantly taller than Everest. Only about 4,207 meters (13,803 feet) of Mauna Kea are visible above sea level, which is why its immense size often goes unnoticed. The common misconception persists because our everyday understanding of a mountain's height is almost always based on its elevation above the ocean's surface, overlooking the massive portions that can extend far below.