In a Nutshell
When discussing mountains, there is a huge difference in definition between ‘tallest’ and ‘highest’. Mount Everest is the highest, but the tallest mountain on earth is actually in Mauna Kea in Hawaii.
The Whole Bushel
When asked what the highest mountain on earth is most would have no problem identifying Mount Everest and they would be completely correct. But when asked about the tallest mountain most would probably say Everest again, not understanding that in mountain measuring terms you just asked them a completely different question. When measuring mountains there are many things to remember. While there is still debate over exactly how to measure a mountain and what even classes as a mountain, there are a few things that persist. The slope, elevation, volume, and steepness among other things all need to be taken into account but them main misconception surrounds height.
Mount Everest is the highest, but the tallest is actually Mauna Kea in Hawaii. This is because ‘highest’ is defined as a measure of mean sea level to summit, while ‘tallest’ is a measurement from the bottom of the mountain to the top. From it’s base to it’s tip, Mauna Kea measures 33,465 feet. In comparison, from base to tip, Mount Everest comes in at a measly 29,029 feet, shorter by more than 4000 feet.
With sea level hypothetically removed from the picture, if the two mountains were placed next to each other Mauna Kea would be taller, but because a huge amount of it is under the sea and invisible to most of us the issue of height becomes blurred. Some even believe Mount Kilimanjaro is taller than everest because it rises straight from the African plain while Everest sits atop the Himalayas.