深海 · ABYSS · Ocean zones
Midnight
Bathypelagic · 1,000 – 4,000 m
Not one photon from the sun reaches this far. Every light you would see below here was made by something alive.
Descend this zone at true scaleDepth 1,000 → 4,000 m
Despite the name, it hunts nothing
The vampire squid lives where there is almost no oxygen. It extends two long filaments, gathers the marine snow that drifts past, binds it with mucus and eats that. Threatened, it turns itself inside out and hides beneath a spined cloak.
Vampyroteuthis infernalis · neither squid nor octopus, but an order of its own
The Bloop
An ultra-low-frequency sound from the South Pacific registered simultaneously on hydrophones 5,000 kilometres apart. It was louder than any known animal. In 2005 NOAA attributed it to an icequake. Julia, Slow Down and Upsweep, recorded in the same years, remain unexplained.
The SOFAR channel — an acoustic duct near 1,000 m where sound travels thousands of kilometres almost undiminished
It hunts by sound
The sperm whale's click reaches 236 decibels, the loudest sound any animal makes. In total darkness the entire hunt is conducted acoustically.
Typical dive 400 – 1,200 m · maximum recorded around 2,250 m
A reef that grows without sunlight
Reefs are not only a shallow tropical thing. Lophelia builds stone in cold black water over thousands of years. One structure off the Norwegian coast runs for 35 kilometres.
Desmophyllum pertusum · being destroyed at scale by bottom trawling
Two bodies become one
The male anglerfish is a twentieth the size of the female. When he finds her he bites and never lets go. Their skin fuses, their blood vessels join, and his eyes and organs dissolve until only the gonads remain. One specimen carried eight males.
Sexual parasitism · an answer to almost never meeting a mate
Giant squid
Its eye is 27 centimetres across, the largest in the animal kingdom. There is only one reason to need an eye that size — to catch the faint glow of plankton disturbed by an approaching sperm whale.
Up to 13 m · first filmed alive in 2004
Deepstaria jellyfish
Its whole body is a giant translucent bag. You can often see what it just ate, still visible through its stomach.
Komsomolets
A Soviet submarine lost to fire still lies on the seabed with its reactor and two nuclear-tipped torpedoes aboard. Norway continues to sample the surrounding water for radioactivity.
42 dead
Its mouth is larger than its body
The pelican eel inflates its jaw like a balloon and swallows prey bigger than itself; the stomach stretches to match. Where meals almost never appear, evolution favoured never missing one.
Eurypharynx pelecanoides · the expansion was not filmed until 2018
Things that live without the sun
Water at 400 °C rises from cracks in the seafloor. The pressure is too great for it to boil, so it stays liquid. Around it live tubeworms and shrimp that use no sunlight at all.
First found at the Galápagos Rift — by geologists, not biologists
A drop that takes 1,000 years
A single drop of seawater takes roughly 1,000 years to complete one loop of the global thermohaline conveyor belt.
The crab that farms
The yeti crab grows bacteria on the hairs of its claws. It waves them over a hydrothermal vent to feed the crop chemicals, then combs the bacteria off and eats them. Agriculture, performed by a crustacean.
Genus Kiwa · first found south of Easter Island in 2005
The ocean is turning more acidic
Ocean acidity has risen about 30% since industrialisation — the price of absorbing carbon dioxide from the air.
Ice that burns
Under cold and pressure, methane becomes trapped inside cages of water molecules and freezes solid. The carbon held this way may exceed all the world's oil, coal and gas combined. Warm the water and it lets go.
Gas hydrate · one cubic metre expands to roughly 164 m³ of methane at the surface
No mouth. No gut. No problem.
The giant tube worm has no mouth, stomach, or anus. Bacteria living inside it oxidize hydrogen sulfide from the vent water into energy, and the worm simply absorbs what's left over.
Lives at hydrothermal vents, roughly 2,000-3,000 m
If you gathered all the ocean's salt
If every gram of dissolved salt in the ocean were spread evenly over land, it would form a layer about 150 metres thick.
USS Thresher
A pipe joint failed during a test dive and the boat lost power. The last transmission was a single garbled sentence. Then listening stations recorded the sound of a pressure hull collapsing. The wreck was found in six pieces.
The loss created SUBSAFE, the U.S. Navy's submarine certification programme
129 dead
Deep-sea gigantism
The giant isopod reaches 50 centimetres. Its shallow-water relatives are the size of a fingernail. Why cold, pressure and scarce food should produce larger bodies is still unsettled. One captive specimen refused food for five years and survived.
Bathynomus giganteus · the textbook case of abyssal gigantism
Even here
Microplastics have been found in the sediment of the Mariana Trench floor — and inside the amphipods that live there.
Ghost mollusc
Only formally named in 2021. Its entire stomach glows, and when threatened it can detach a glowing piece of gut as a decoy.
Three hours 42 minutes without breathing
A Cuvier's beaked whale was recorded at 2,992 metres. Another stayed under for three hours and forty-two minutes on a single breath — the longest dive by any mammal.
How it is possible has never been fully explained
USS Scorpion
Lost in the Atlantic in 1968. Ninety-nine men died and the cause has never been settled.
Titan
A tourist submersible lost contact one hour and forty-five minutes into its descent. An international search ran for four days while the press counted down the oxygen supply by the hour. It had already ended at the moment contact was lost — an implosion completes in about 30 milliseconds.
Faster than a human brain can register that anything has happened
5 dead
The commonest fish down here
Grenadiers patrol just above the mud, following the smell of carrion. Nothing about them is spectacular or frightening, yet they account for much of the fish biomass on the deep seafloor. The default deep-sea animal is not a monster. It is this.
Family Macrouridae · roughly 400 species
Sound moves four times faster here
Sound travels about 4.3 times faster through water than through air — denser medium, faster vibration.
Containers that fell
More than a thousand shipping containers are lost overboard each year, and most are never recovered. The 28,000 rubber ducks spilled into the Pacific in 1992 are still used as markers in ocean-current research.
World Shipping Council annual figures · most resting places unknown
The longest mountain range on Earth
The mid-ocean ridge system runs about 65,000 kilometres — the longest mountain range on Earth, and almost entirely underwater.
Titanic
The ship broke in two at the surface and the halves sank at different rates, landing 600 metres apart. For 73 years nobody knew where. When Robert Ballard found her in 1985 he was on a classified navy mission to survey two lost nuclear submarines.
Iron-eating bacteria are consuming the hull · she may lose her shape by the 2030s
About 1,500 dead
Faceless cusk
First hauled up by HMS Challenger in 1873, then unseen for over a century until it was filmed again off Australia in 2017. Its eyes and mouth are almost buried under skin.
The ocean is 4 billion years old
Liquid oceans have existed on Earth for roughly 4 billion years — longer than life itself.
The limit of its era
- 1,370 m Benthoscope — the limit of human reach
- 3,150 m Trieste — the limit of human reach
What fits in this depth
| Depth | |
|---|---|
| 1,857 m | Grand Canyon (deepest point) |
| 1,915 m | Jirisan |
| 1,947 m | Hallasan |
| 2,744 m | Paektusan |
| 3,441 m | Mean depth of the world ocean |
| 3,776 m | Mount Fuji |
Figures come from public observational data; sources are cited in the main descent. Do not use for navigation, diving, or any safety decision.