The deep ocean remains one of Earth's least explored frontiers, covering 66% of the planet's surface yet largely unmapped. The search for Malaysia Airlines flight MH370, which disappeared in March 2014, revealed how little we know: mapping a 1,500-mile stretch of the southern Indian Ocean uncovered undersea canyons, volcanic plateaux and a cliff taller than the Swiss Alps.
At current rates, a complete visual survey of the ocean floor would take 5 million years. Yet the deep sea plays a vital role in regulating our climate, absorbing 30% of atmospheric carbon dioxide and generating 80% of the world's oxygen. As physicist Helen Czerski notes in her book The Blue Machine, the oceans drive the weather systems that sustain life on land.
The deep ocean is also home to extraordinary lifeforms adapted to crushing pressures, extreme temperatures and total darkness. Recent expeditions have discovered over 1,100 new marine species, including a ghost shark, a ping-pong ball sponge, and a mysterious jelly-like organism that defies classification. Hydrothermal vents, or 'black smokers', spew superheated, toxic water yet support vibrant ecosystems that may hold clues to the origins of life.
However, these fragile habitats face growing threats from deep-sea mining and overfishing. With extractive industries pushing into ever deeper waters, scientists warn that unique species and ecosystems could be lost before they are even studied. The deep ocean, our planet's largest and least understood ecosystem, is at risk of being irreversibly damaged.
