The ocean is layered like a cake of darkness. Scroll down to descend through all five zones — the further you go, the colder, blacker, and stranger it gets. Watch the gauge.
Sunlight pours in, plankton bloom, and photosynthesis powers nearly everything. This thin bright lid holds the coral reefs, the tuna, the dolphins — the vast majority of life you've ever seen in the sea.
Only a faint blue glow survives here. Animals start making their own light — bioluminescence — to hunt, hide, and find mates. Lanternfish in this layer may outweigh every other fish in the ocean combined.
Total, permanent darkness. Near-freezing water and pressure that would crush a submarine. Food is so scarce that mouths are enormous and the anglerfish dangles a glowing lure to bring dinner to it.
From the Greek ábyssos, "bottomless." Just above freezing, pitch black, and under 600 atmospheres of pressure. Sea pigs, ghostly cucumbers, and tripod fish wander a silty plain that covers more of Earth than every continent.
The deepest scars on the planet. At the bottom of the Mariana Trench the pressure is over a thousand times that at the surface. And yet — snailfish, amphipods, and microbes still make a living down here, in the most alien place on Earth.