Ten kilometresdown

The open ocean is stacked in five layers, each darker, colder and heavier than the last. Scroll to sink through all of them, from sunlit water to the bottom of the Mariana Trench.

Start the descent

0 to 200 metres

The sunlight zone

Almost all ocean life depends on this thin, bright skin of water. Here, enough light reaches the water for drifting algae to photosynthesise, and those microscopic plants make roughly half the oxygen on Earth.

By 200 metres, only about one per cent of the surface light is left. Red goes first, then orange and yellow, until the water glows a deep, even blue.

Light
100 to 1%
Temperature
Up to 30 °C
Pressure
1–21 atm
Illustration of diatoms, single-celled algae with glassy, patterned shells
Diatoms: single cells in shells of glass. Trillions of them drift in the sunlight zone.

200 to 1,000 metres

The twilight zone

There is light here, but too little to grow anything. Animals hide in the gloom by day. When night falls, many of them swim hundreds of metres up to feed near the surface, then sink back before dawn.

That nightly commute happens all over the world at once. Counted by the number of animals, it is the largest migration on the planet.

Light
Faint blue
Temperature
4–20 °C
Pressure
21–101 atm
Illustration of a lanternfish with rows of glowing spots along its belly
Lanternfish, among the most numerous fish on Earth. The lights on its belly match the glow from above, erasing its silhouette.

1,000 to 4,000 metres

The midnight zone

No sunlight reaches this far. The only light is made by animals: flashes to startle a predator, glowing lures to draw in prey, signals to find a mate in the dark.

In surveys of the open water column, about three in every four animals seen could make their own light.

Light
None
Temperature
About 4 °C
Pressure
101–401 atm

Move your cursor, or drag a finger, through this water to see it light up.

Illustration of an anglerfish with a glowing lure hanging in front of its open, toothed mouth
A female anglerfish. The lure on her head is lit by glowing bacteria living inside it.

4,000 to 6,000 metres

The abyss

Most of the deep seafloor lies at this depth: the abyssal plains, vast stretches of soft mud that are among the flattest places on Earth.

Food arrives as marine snow, a slow drizzle of dead plankton, droppings and dust from the waters above. Some flakes take weeks to fall this far.

Light
None
Temperature
2–3 °C
Pressure
401–601 atm
Illustration of a dumbo octopus, with ear-like fins and a webbed skirt of arms
A dumbo octopus hovers above the mud, rowing with the two fins that give it its name.

6,000 to 10,935 metres

The hadal zone

Below the abyss, the seafloor splits into trenches where one tectonic plate dives under another. Named after Hades, these are the deepest places in the ocean, and fewer people have visited their floors than have walked on the Moon’s surface.

At the bottom of the Challenger Deep, the water presses down with more than a tonne on every square centimetre. Life is still there.

Light
None
Temperature
1–4 °C
Pressure
601–1,095 atm
Illustration of a pale, translucent hadal snailfish with a broad head and long tapering tail
Hadal snailfish have been filmed swimming at over 8,300 metres, deeper than any other fish on record.