深海 · ABYSS · Ocean zones
Sunlit
Epipelagic · 0 – 200 m
The only layer where photosynthesis happens. It holds 2% of the ocean's volume and almost every image you have of the sea.
Descend this zone at true scaleDepth 0 → 200 m
Red disappears
Water absorbs long wavelengths first. Cut yourself at this depth and the blood runs a greenish black.
Mesophotic coral
Coral still grows where the light has nearly gone. One hypothesis holds that these reefs could act as a gene bank when the shallow ones bleach.
Continental shelf
It is barely 7% of the seafloor, yet most of the world's catch comes from here. This is the drowned edge of a continent — during the ice ages you could have walked across it.
Average depth 60 m · the edge usually breaks away near 140 m
Where oxygen turns toxic
Under pressure, pure oxygen causes convulsions. From 30 metres down nitrogen acts as an anaesthetic — divers get drunk without knowing they are drunk.
Whale shark
Up to 18 metres, the largest fish alive, feeding on plankton and diving to 1,900 metres. Individuals are identified by an algorithm NASA wrote for matching star fields.
Kursk
A torpedo explosion put the nuclear submarine K-141 on the seabed at 108 metres. Twenty-three men were alive in the ninth compartment. A note one of them wrote in the dark was found later. No rescue arrived.
118 dead
The most abundant photosynthesiser on Earth
Prochlorococcus was not discovered until 1988. It is 0.6 micrometres across, and a single drop of seawater holds hundreds of thousands of them. It was simply too small for anyone to see for two centuries of oceanography.
Around 10²⁷ cells · 5 – 10% of all marine primary production
Submarine cables
99% of internet traffic passes through 1.4 million kilometres of cable on the seabed. The most common cause of a break is not sharks but trawl nets and anchors.
Blue whale
33 metres, 190 tonnes — the largest animal that has ever existed, and it is still here. Its heart is the size of a person; its call carries hundreds of kilometres at 188 decibels. It comes down this far for krill.
Around 10,000 – 25,000 remain
What fits in this depth
| Depth | |
|---|---|
| 51 m | Niagara Falls (drop) |
| 93 m | Statue of Liberty (with pedestal) |
| 135 m | London Eye |
| 169 m | Washington Monument |
Figures come from public observational data; sources are cited in the main descent. Do not use for navigation, diving, or any safety decision.