Put Everest in Challenger Deep and its summit would still be about 2.1 km underwater.

Earth's highest summit and its deepest known seafloor are usually measured in opposite directions from sea level. Line them up on the same reference, and the ocean wins — by more than two kilometres.

Challenger Deep's deepest observed seafloor is 10,935 m (±6 m) below mean sea level. Everest's summit is 8,848.86 m above it.

Subtract one from the other and about 2.1 km is left over. The trench depth carries a ±6 m uncertainty, so the result shouldn't be read to the centimetre.

This is a datum-aligned thought experiment. It doesn't mean Everest would physically fit inside the trench, or that the trench is shaped like a mountain.

Challenger Deep depth

10,935 m (±6 m)Source value

Below mean sea level

Everest elevation

8,848.86 mSource value

Jointly announced by Nepal and China, 2020

Difference

10,935 − 8,848.86 = 2,086.14 mCalculated

Published

≈2.1 km underwaterResult

Rounded — the ±6 m depth doesn't support centimetres

Derived comparison from authoritative reference values. Challenger Deep from NOAA-supported research (±6 m), Everest from the 2020 Nepal–China announcement. The subtraction is Scaleidoscope's, rounded to about 2.1 km because the depth input carries uncertainty.

Derived by us from two published values; the Challenger Deep depth is treated as approximate. No source states this comparison directly.

• NOAA

  Challenger Deep(opens external site)

• Survey of Nepal / China

  Everest summit elevation 8,848.86 m
• Reuters (news report; measured by the joint Nepal–China 2020 survey)(opens external site)

• NOAA Institutional Repository

  Revised depth of the Challenger Deep from submersible transects (Greenaway et al., 2021)(opens external site)

  Deepest observed depth 10,935 m (±6 m at 95% C.I.)

• Survey Department, Government of Nepal

  Measurement of Height of Mt. Sagarmatha (Dangol et al.)(opens external site)

  Orthometric height 8,848.86 m

• Scaleidoscope

  Scaleidoscope derived calculation from sourced official dimensions

  Scaleidoscope arithmetic from the sourced inputs

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