Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
1,090,000,000
people
How to estimate it
Fermi’s official “Napkin math”
The easiest place to start is the world population, about 8 billion. How many of them live close enough to the ocean to see it on a clear day? Coasts pull people in for fishing, trade, and tourism, so call it 1 in 7.
- World population
- ~8,000,000,000
- Live within 10km of a coast
- ~1 in 7
- 8B ÷ 7
- ≈ 1.1 billion
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- People within 5 km (3 miles) of a coast, 2018 (LandScan data)
- 748,000,000
- People 5 to 10 km (3 to 6 miles) from a coast
- + 344,000,000
- 748M + 344M
- ≈ 1.09 billion
Reference cited by Fermi: Scientific Reports (Nature), "Accelerating growth of human coastal populations at the global and continent levels: 2000-2018" (Cosby et al., Mississippi State University / Oak Ridge National Laboratory LandScan data)
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