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Hadal

A dive from the surface of the western Pacific to the bottom of the Challenger Deep, 10,935 m down. Scroll to descend.

Hadal is a fictional expedition. The submersible and crew are invented; the depths, measurements and animals are real.

Begin the descent

Step 1: Sunlight zone

Nearly all the ocean's light, and most of the life we know

Sunlight powers everything here. Drifting plankton turn it into food, and in doing so they make roughly half of the oxygen produced on Earth. It is also the only part of the ocean most people ever see.

Depth
0 m to 200 m
Pressure
1 atm to 21 atm
Temperature
29.0 °C to 18.0 °C

Oceanographers call it the epipelagic zone.

  1. 10 m

    Ten metres down the pressure has already doubled: one atmosphere of air above the sea, and one more of water.

  2. 90 m

    Water absorbs red light first, then orange and yellow. By now the world is blue-green, and a red fish looks grey.

  3. 150 m

    The thermocline. Warm surface water gives way quickly to the cold of the deep, and the two barely mix.

Step 2: Twilight zone

Too dim for plants, bright enough to be seen by

Below 200 metres there isn't enough light for photosynthesis, only a fading blue from above. So animals make their own: about four in five living at these depths can produce light.

Depth
200 m to 1,000 m
Pressure
21 atm to 99 atm
Temperature
18.0 °C to 4.4 °C

Oceanographers call it the mesopelagic zone.

  1. 320 m

    Lanternfish, small fish studded with rows of light organs, are among the most common and varied fish in the open ocean.

  2. 550 m

    Some animals glow on their undersides to match the light filtering down, so a hunter looking up sees no silhouette.

  3. 750 m

    Every night lanternfish and many other animals rise toward the surface to feed in the dark, then sink back before dawn. It is often called the largest migration on Earth.

Step 3: Midnight zone

From here down, almost every light is alive

No sunlight reaches below about 1,000 metres. The water is close to 4 °C and the pressure is a hundred times what it is at the surface. Food is scarce, so many animals wait instead of chasing.

Depth
1,000 m to 4,000 m
Pressure
99 atm to 393 atm
Temperature
4.4 °C to 1.5 °C

Oceanographers call it the bathypelagic zone.

  1. 1,500 m

    A female anglerfish dangles a glowing lure over her mouth. The light comes from bacteria living inside the lure, and it draws prey close enough to swallow.

  2. 2,400 m

    Many animals down here are red or black. Red light never reaches this deep, so a red body is as dark as a black one.

  3. 3,682 m

    The average depth of the ocean. Everything below us now is deeper than average.

Step 4: Abyssal zone

A slow snowfall that never stops

Most of the food here falls from above as marine snow: flakes of dead plankton, waste, sand and dust drifting down from the sunlit water. Some flakes take weeks to arrive. The water hovers around 1.5 °C.

Depth
4,000 m to 6,000 m
Pressure
393 atm to 589 atm
Temperature
1.5 °C to 1.6 °C

Oceanographers call it the abyssopelagic zone.

  1. 4,600 m

    Most of the deep sea floor lies between 3,000 and 6,000 metres, in wide, quiet plains of soft mud.

  2. 5,200 m

    Dumbo octopuses hover over the floor, steering with ear-like fins. One was filmed at 6,957 metres, the deepest any octopus has been seen.

  3. 5,900 m

    Pressure here is close to 600 atmospheres. Animals cope because their bodies are mostly water, which barely squeezes smaller however hard it is pressed.

Step 5: Hadal zone

Below the abyss, only the trenches go on

Deeper than 6,000 metres, the ocean exists only in trenches, carved where one plate of Earth's crust slides beneath another. The zone is named after Hades, the Greek underworld, and it is among the least explored places on the planet.

Depth
6,000 m to 10,935 m
Pressure
589 atm to 1,072 atm
Temperature
1.6 °C to 2.5 °C

Oceanographers call it the hadalpelagic zone.

  1. 7,000 m

    The walls close in. The Mariana Trench is a crescent-shaped scar more than 2,500 kilometres long, where the Pacific plate sinks under the Mariana plate.

  2. 8,178 m

    The Mariana snailfish, pale, scaleless and soft, was filmed this deep in 2017. Scientists think fish can't live much below about 8,200 to 8,400 metres; the deepest yet filmed, another snailfish off Japan, was at 8,336.

  3. 9,800 m

    Below the fish, scavengers take over: shrimp-like amphipods a few centimetres long, which swarm to anything that falls.

  4. 10,500 m

    Past 4,000 metres the water slowly warms again, by about one degree, because the weight of the water above squeezes and heats it.

Step 6: The bottom of the Challenger Deep

Nearly eleven kilometres of water overhead, pressing down at more than a thousand times the pressure at the surface. The first people to reach this floor were Jacques Piccard and Don Walsh, in the bathyscaphe Trieste, in 1960. Only a small number of crewed dives have reached it since.

Depth
10,935 m
Pressure
1,072 atm
Temperature
2.5 °C

In this story, DSV Plumb settles here for an hour before the climb back. The vessel and its crew are invented; the place is not.

Return to the surface