Mount Analogue is a very tall mountain, towering from the Pacific Ocean and is possibly to be the largest tallest mountain on Earth. However, its existence is, to the greater percentage of Earth's population, utterly unknown. This is given to the space around Mount Analogue that is strangely curved in such a way that even light-rays bend around the island, rendering it effectively invisible.
Source material
Mount Analogue is from René Daumal's Le Mont Analogue (1952).