• Humans have visually observed only 0.001% of the deep seafloor, equivalent to the size of Rhode Island, according to a recent study published in Science Advances.
• Exploration efforts are heavily biased towards areas near the United States, Japan, and New Zealand, with limited exploration in other regions like the Indian Ocean.
• The study underscores the need for increased exploration and research to understand the deep sea's role in climate regulation, oxygen production, and potential impacts of deep-sea mining.

A new study published in Science Advances reveals that humans have visually explored only a tiny fraction, 0.001%, of the deep seafloor. This area is approximately the size of Rhode Island. The study, analyzing over 43,000 deep-sea dives since 1958, highlights the vast unknown aspects of Earth's largest biome and raises concerns about the limited data available for making informed decisions on climate change, deep-sea mining, and biodiversity.

• What: A study revealing that humans have visually observed only 0.001% of the deep seafloor.
• Who: Katy Croff Bell of the Ocean Discovery League led the study. Jeffrey Karson of Syracuse University provided expert commentary. Susan Poulton is a researcher at the Ocean Discovery League and co-author of the paper.
• When: The study was published in May 2025 and analyzed data from deep-sea dives conducted since 1958. As of June 2024, 26.1% of the global seafloor has been mapped.
• Where: The deep seafloor, globally, with a bias in exploration towards areas within 200 nautical miles of the United States, Japan, and New Zealand. The Indian Ocean is one of the least explored areas.

The extremely small fraction of the deep seafloor that has been visually explored highlights a significant gap in our understanding of Earth's largest biome. This lack of knowledge raises concerns about the potential environmental impacts of activities like deep-sea mining and the ability to make informed decisions about climate change, especially given the deep sea's role in absorbing heat and carbon dioxide. The biased nature of exploration efforts, concentrated near a few countries, further limits the representativeness of current knowledge. This study calls for a fundamental shift in how we approach deep-sea exploration, emphasizing the need for more diverse participation and the development of low-cost technologies to facilitate broader exploration.

The fact of the matter is, when you're down there with a remotely operated vehicle or other sort of deep-submergence vehicle, you can only see a very tiny bit of the deep sea floor at any one time.

It’s like if we were to make all assumptions about terrestrial ecosystems from observations of 0.001% of land area, that would equate to smaller than the land area of Houston, Texas.

Almost every time we go there, we learn something new and exciting, and many of our discoveries on the seafloor have been serendipitous. So, you know, we're feeling our way in the dark, literally, there.

This small and biased sample is problematic when attempting to characterize, understand, and manage a global ocean

More information is always beneficial, so we can make more informed and better decisions.

The shockingly limited visual exploration of the deep seafloor reveals a compelling demand for intensified, globally collaborative research efforts prioritizing unexplored regions and accessible technologies. Addressing funding gaps, vessel access, and human capacity limitations is crucial for equitable participation. This imperative is amplified by the deep sea's critical role in climate regulation and the potential for irreversible impacts from activities like deep-sea mining, which can cause habitat destruction, biodiversity loss, and disruptions to carbon sequestration. Future exploration must integrate innovative technologies like AI and autonomous underwater vehicles while also addressing hardware challenges such as high pressure and corrosive saltwater. Sustainable practices, interdisciplinary collaboration, and comprehensive regulatory frameworks are essential to balance resource demands with responsible stewardship, ensuring the preservation of deep-sea ecosystems and the equitable sharing of benefits.