In the depths off Japan's coast, a mission is underway to discover life forms never before seen by science, revealing the ocean's critical role in our future.
The ocean covers over 70% of our planet, yet over 90% of its species remain undocumented10. As a nation surrounded by the sea, Japan is at the forefront of the race to close this profound knowledge gap. Japanese researchers are exploring mysterious deep-sea ecosystems, decoding the ocean's influence on global climate, and discovering new life forms at an unprecedented pace. This is not just a journey of discovery but a mission critical for the preservation of our planet's biodiversity and the health of our global environment.
In the summer of 2025, a groundbreaking 20-day scientific voyage set sail aboard the Japanese research vessel Yokosuka, marking Japan's flagship contribution to the Ocean Census—the world's largest program to accelerate marine species discovery2.
"This expedition represents more than a journey into the unknown; it signifies a convergence of knowledge, expertise, and a shared vision dedicated to advancing the discovery of marine biodiversity."
The expedition is focused on biologically rich, mysterious deep-sea regions within Japan's Exclusive Economic Zone, including the Nankai Trough and Shichiyo Seamounts2. At the heart of this mission is Japan's renowned submersible, Shinkai 6500, one of the world's deepest-diving human-occupied research submersibles, capable of reaching depths of 6,500 meters2.
Since its inception in 1990, this engineering marvel has completed over 1,800 dives, symbolizing Japan's decades-long commitment to deep-sea expertise2.
Maximum diving depth of the Shinkai 6500 submersible2
Completed by Shinkai 6500 since its launch in 19902
Duration of the Ocean Census expedition aboard RV Yokosuka2
While the discovery of new species captures the imagination, Japanese researchers are also leading efforts to understand the ocean's fundamental role in regulating global climate.
Research at Hokkaido University's Laboratory of Physical Oceanography and Climate revealed how the Kuroshio Extension—one of the world's fastest currents—influences coastal sea-level changes along Japan8. This discovery highlights the importance of understanding western boundary currents for reliable prediction of future coastal sea level changes.
A landmark study discovered that the Gulf Stream in the Atlantic significantly influences the troposphere, a finding that graced the cover of Nature in March 20088. Subsequent research found that precipitation associated with the Early Summer Baiu rainband is enhanced over the warm sea surface temperature of the Kuroshio Current in the East China Sea8.
Japanese scientists have identified a penta-decadal (50-70 year) climate oscillation over the North Pacific, research that has been cited in the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC)8. These decadal variations are synchronized with 20-year climate cycles and may represent climate regime shifts with global implications8.
At JAMSTEC's Physical and Chemical Oceanography Research Group, scientists are analyzing highly accurate shipboard observation data to detect subtle but significant changes in the global ocean environment4.
Their work includes "quantitative ocean observation experiments" in the North Pacific and interdisciplinary global observations that link physical and chemical oceanography4. This research is crucial for understanding how the ocean absorbs and stores carbon dioxide, with profound implications for climate change projections4.
The ongoing Ocean Census expedition exemplifies the cutting-edge methodologies Japanese scientists are using to explore the deep sea.
The primary objective is to discover and document marine species in Japan's unexplored deep-sea ecosystems, contributing to the global Ocean Census goal of dramatically accelerating the pace of marine species discovery210.
While the 2025 expedition is ongoing, the Ocean Census program has already demonstrated remarkable success globally, having discovered 866 new marine species in its initial phases10. These include a rare guitar shark, a marine gastropod with potential biomedical applications, and a new octocoral from the Maldives10.
Type: Elasmobranch
Discovery Location: Mozambique and Tanzania waters
Significance: Only the 38th known guitar shark species; 2/3 of related species are threatened10
Type: Gastropod
Discovery Location: Off New Caledonia and Vanuatu
Significance: Venom contains peptides with potential pain relief and cancer treatment applications10
Japanese oceanography relies on a sophisticated array of technologies and methodologies that enable research across the vast and challenging marine environment.
Function: Manned submersible for direct deep-sea observation and sampling
Application: Exploring the Nankai Trough at 6,500m depth for new species2
Function: Mobile platforms for deploying equipment and conducting extended missions
Application: Supporting the 20-day Ocean Census expedition with labs and submersible deployment2
Function: Unmanned, tethered robots for deep-sea exploration without human risk
Application: Surveying submarine caves on Minamidaito Island6
The commitment to open science ensures that all discoveries from these expeditions are made freely available through platforms like the Ocean Census Biodiversity Data Platform2. This collaborative approach extends to international partnerships, such as the long-running Japanese-French Oceanography Symposium, which promotes scientific exchanges between the two nations5.
As the Ocean Census expedition continues its work, the future of Japanese oceanography appears increasingly interdisciplinary.
The newly established Center for Coupled Ocean-Atmosphere Research (CCOAR) at JAMSTEC focuses on understanding the coupled ocean-atmosphere system as the key to predicting extreme weather events9. This research is vital for a country like Japan, which faces serious concerns from extreme events with heavy rainfall caused by tropical cyclones and atmospheric rivers9.
Meanwhile, the integration of physical oceanography with biogeochemical studies is opening new frontiers. Japanese scientists are beginning to investigate large-scale variations of oceanic nutrients and oxygen, crucial research areas given that reduced ocean mixing due to global warming could limit nutrient transport and potentially disrupt entire marine ecosystems8.
| Institution | Focus Areas | Notable Programs/Projects |
|---|---|---|
| JAMSTEC | Deep-sea exploration, climate research, ocean-atmosphere coupling | Shinkai 6500 operations, Ocean Census partnership, OFES workshops247 |
| Hokkaido University | Physical oceanography, climate variability, air-sea interaction | Laboratory of Physical Oceanography and Climate8 |
| Japan Hydrographic Association | Marine data management, quality control, public dissemination | Japan Oceanographic Data Center (JODC)3 |
Japan's oceanographical research embodies a powerful combination of technological innovation, international collaboration, and unwavering curiosity.
From the deep-sea discoveries of the Ocean Census expedition to the climate insights generated by decades of precise observation, Japanese scientists are dramatically expanding our understanding of the marine world.
"Japan's waters hold extraordinary biological diversity, and many areas remain virtually unexplored"2
Each dive of the Shinkai 6500, each data point collected by research vessels, and each new species identified brings us closer to understanding the ocean's critical role in sustaining our planet.
The journey into the deep is more than a scientific pursuit—it is an essential mission to understand and protect the heart of our blue planet, and Japan is leading the way into the abyss, one discovery at a time.