The unmapped frontier
The ocean covers 71% of Earth's surface and has an average depth of 3,688 metres. Below 200 m — the limit of significant sunlight — lies the deep ocean: cold, under extreme pressure, and almost entirely dark. Yet it supports a staggering diversity of life.
The Seabed 2030 project, a collaboration between the Nippon Foundation and GEBCO, aims to map the entire ocean floor to a resolution of 100 metres by 2030. As of mid-2026, the project has mapped approximately 26% — up from 6% when it started in 2017.
Life without sunlight
The discovery of hydrothermal vents in 1977 overturned a basic assumption of biology: that all life ultimately depends on photosynthesis. Vent ecosystems run on chemosynthesis — bacteria oxidise hydrogen sulfide from the vent fluid to power carbon fixation, forming the base of a food chain that supports tube worms up to two metres long, giant clams, blind shrimp and several fish species.
Cold seeps — areas where methane and hydrogen sulfide seep slowly from the seafloor — host similarly rich communities. The biological diversity of these systems, combined with the fact that similar chemistry may exist beneath the ice-covered oceans of Europa and Enceladus, makes them a key reference for astrobiology.
For how cellular metabolism works, see our cells and organelles guide.
Recent discoveries
A 2023 Schmidt Ocean Institute expedition to the Clarion-Clipperton Zone in the Pacific found over 100 species new to science in a survey of a proposed deep-sea mining area. The survey found that the region hosted more biodiversity than expected — and that almost all species were unique to the zone, found nowhere else.
In the Atacama Trench (off the coast of Chile), researchers have documented amphipod crustaceans, polychaete worms and bacteria that thrive under pressures exceeding 600 atmospheres. Enzymes from piezophilic (pressure-loving) microbes have potential industrial applications.
The natural selection operating in these extreme environments — isolated, stable, chemically distinct — has produced organisms with biochemistry unlike anything in surface ecosystems. For more on how populations diverge under different pressures, see our natural selection guide.
Pharmaceutical potential
Deep-sea organisms produce bioactive compounds adapted to their unusual environment — high pressure, near-freezing temperatures, complete darkness and often high concentrations of metals or sulfur. Several approved drugs originate from marine organisms, including cytarabine (from a Caribbean sponge) used in leukaemia treatment and ziconotide (from cone snail venom) used for severe pain.
The Taq polymerase enzyme from Thermus aquaticus — isolated from hot springs, an analogous extreme environment — made PCR (polymerase chain reaction) possible, underpinning all of modern molecular biology including CRISPR gene editing.