0 metres
Sunlight
Everything is still visible here.
200 metres
Twilight
Blue eats the other colours.
1 000 metres
Midnight
Where sunlight ends. Every light below this is made by something alive.
4 000 metres
Abyss
Four hundred atmospheres. Two degrees. Permanent night.
10 924 metres
Challenger
Deep
Fewer people have come here than have walked on the Moon.