In May 2026, the Ocean Census released its most comprehensive annual report to date. Scientists from thirteen expeditions and nine species discovery workshops described 1,121 new marine species. The startling message lies in a different number: up to 90 percent of all marine species remain completely unknown to science. The ocean is no well-mapped terrain. It is Earth's largest unexplored territory.
What the Ocean Census is
The Ocean Census was founded in 2022 as a collaboration between Japan's Nippon Foundation and Britain's Nekton marine research institute. Its goal is to catalogue as many unknown marine species as possible by 2030. Hundreds of scientists from dozens of countries are involved, including Australia's CSIRO research institute, the Scripps Institution of Oceanography at the University of California San Diego, and the Senckenberg Institute for Natural Research.
For the 2026 annual report, researchers analyzed approximately 48 million datasets containing information on 184,000 already-known marine species. The newly described 1,121 species are added to this. From the Coral Sea north of Australia alone, CSIRO reported more than 110 new species: fish, invertebrates, and microorganisms without known names.
Why 2026 is special for marine research
This year's discoveries come from unusually diverse ecosystems. New coral reef fish species were mapped in shallow tropical coastal waters. In the so-called twilight zone, depths between 200 and 1,000 meters, researchers found species not directly exposed to sunlight but critical for nutrient cycles of the entire water column. In the hadal zones of the deepest Pacific trenches, worm-like organisms were described that withstand pressures exceeding 600 bar.
Among the most remarkable new discoveries is the "Iskra's Glitter Worm," a newly described deep-sea worm whose metallically shimmering bristles hint at a previously unknown armor function of the body. A new tunicate species from depths below 4,000 meters was also documented. Tunicates are regarded as distant relatives of all vertebrates and are crucial for understanding early evolutionary stages.
What it means that 90 percent are unknown
Hanieh Saeedi from the Senckenberg Institute for Natural Research leads the Census's biodiversity measurement group. Her studies show that knowledge gaps are largest where biological diversity is highest: in tropical marine regions near the equator. Less than 2.5 percent of all recorded biodiversity data comes from these areas. Rich ecosystems and poor data go hand in hand.
For comparison: approximately 95 percent of land mammal species are known and named. In the ocean, the figure is 10 to 20 percent. The ocean covers more than 70 percent of Earth's surface and, by estimates, contains between 700,000 and one million different animal species. Fewer than one-fifth of these have ever been described.
A race against time: deep-sea mining and climate change
Why is this more than an academic number? Because species conservation only works if species are known. The UN High Seas Agreement (BBNJ), signed by more than 100 countries in 2023, requires environmental impact assessments for economic activities in international ocean spaces. But how can such an assessment work when 90 percent of affected species are unknown?
This applies especially to deep-sea mining. More than a dozen countries have issued licenses for extracting manganese nodules and cobalt crusts in international waters, in regions science barely knows. The Census 2026 report explicitly describes the race: as economic activity pushes into unknown deep-sea zones, it becomes increasingly urgent to at least know which species live there before they disappear. Add climate change to this: rising ocean temperatures and ocean acidification affect species not yet described. They cannot be protected.
Until 2030: what the program still plans
The Nippon Foundation and Nekton designed the Census with a ten-year horizon. Expeditions to the Indian Ocean are planned for 2027, one of the least-mapped deep-sea zones worldwide. The Census increasingly relies on automated underwater vehicles and environmental DNA analysis (eDNA), methods that allow species to be identified solely through genetic traces in the water without physically capturing them.
For the 1,121 newly described species, the real work begins after discovery: formal naming, classification, and publication in peer-reviewed journals. This process takes several years per species on average. It is a systemic delay. Earth discovers its own inhabitants faster than science can capture them.