Mount Everest isn't the tallest mountain on Earth.

[Krobilus]

Mauna Kea and Mauna Loa in Hawaii, the twin volcanoes, are taller than Mount Everest due to 4.2km of their heights being submerged underwater. The twin volcanoes measure a staggering 10.2km in total, compared to Everest’s paltry 4.6km.

 

[Sneaky2021]

Oh. I see. It is submerged in water. How tall can those volcanoes if ever not? Mt. Everest is already famous and well known for how tall it is.