science_blog_fun

How much water would it take to drown Mt. Everest?

Let us wildly oversimplify the Earth as a perfect sphere, pretend all land is exactly at sea level, and then pour on the water until Mount Everest’s summit (8 848 m) disappears under a global bathtub.^[1]

1. The rough‑and‑ready math

Earth’s surface area
$A = 4\pi R^2$, with $R ≈ 6\,371\text{ km}$.
$ A \;\approx\; 4\pi (6\,371)^2 \;\approx\; 510\times10^6\;\text{km}^2 $
Desired flood depth
$H = 8.848\text{ km}$ (Everest above “sea” level).
Volume of water

V = A × H ≈ (510 × 10^6 km²) × (8.848 km) ≈ 4.5 × 10^9 km³

That’s 4.5 billion cubic kilometers of water.

2. Putting it in perspective

Current global water (all oceans, ice caps, groundwater):
~1.39 billion km³.
Extra water needed:
$4.5 - 1.39 ≈ 3.1$ billion km³.
If you could import water from Mars, you’d need roughly three times all the water that’s already on Earth today.

3. What does that look like?

┌─────────────────────────────────────────────┐
│                                             │
│      🌊 Ever-Deepening Global Bathtub       │
│                                             │
│      ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓        │
│      ┃ 8 848 m — Everest summit 🏔 ┃        │
│      ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛        │
│      \~4.5×10^9 km³ total water added       │
│                                             │
└─────────────────────────────────────────────┘

4. The fine print (aka “real‑world gets messy”)

Topography matters. In reality, some land is below 8 848 m, some is far below sea level, some far above. You’d need slightly less water than our “perfect sphere” estimate, but still on the order of a few billion cubic kilometers.
Water source logistics. Even if you found a cosmic firehose, it’d need to pump at roughly $1.4×10^{14}$ m³/day for 10 million years to finish the job.
Climate chaos. Before you’re done, the oceans would boil off, the crust would fracture, and you’d have bigger problems than drowning Everest.

Answer: You’d need on the order of 4.5 billion km³ of extra water – roughly three times the volume of all water currently on Earth – to submerge Mount Everest under a perfectly flat global sea.

This assumes no existing ocean depth and ignores every other geographic complication.