The deepest point in the ocean is deeper than Mount Everest is tall.
Why it is true
The Challenger Deep, in the Mariana Trench, reaches about 11,000 metres deep. Mount Everest is 8,849 metres high. If we placed the mountain inside the trench, its peak would still be more than two kilometres below the water surface.
Source: NOAA
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This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.