Humans have seen just 0.001% of the deep-sea floor. Scientists call for urgent exploration

Humans have directly observed just one-thousandth of one percent of the ocean floor in what scientists define as the deep-sea zone. Very little is known about the biodiversity in these regions — many of which are facing imminent exploration and exploitation, researchers warn.

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10 may 2025   |   11:35   |   Source: PAP / Gazeta Morska   |   Prepared by: Kamil Kusier   |   Print

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Deep-sea areas, defined as ocean zones lying below 200 meters, are far from being underwater deserts. They host a wide range of ecosystems that offer real benefits to humanity. These systems provide essential ecosystem services such as oxygen production and climate regulation, and they have yielded discoveries crucial to medical research. This vast region also plays a critical role in maintaining the overall health of the planet.

Yet, research on these deep ecosystems remains severely limited. Scientists emphasize that the vast majority of these areas have never been seen — not directly by human eyes through submersibles or dives, nor even through visual recordings captured by autonomous devices. Currently, images from the deep sea are limited to select regions near just a handful of countries.

However, image capture — including filming and specialized photography — alongside seabed mapping and sample analysis, forms the backbone of oceanographic research, note scientists from the Ocean Discovery League, authors of a study published in Science Advances.

They highlight that deep-sea areas matching the formal definition of “deep” account for around 66% of the Earth's surface. Yet they remain largely uncharted. Despite decades of ocean exploration, humans have visually observed less than 0.001% of the deep-sea floor — an area roughly equivalent to just one-tenth the size of a small country like Belgium.

- As threats to deep-sea preservation accelerate — from climate change to deep-sea mining and resource exploitation — such limited knowledge of such a vast region is becoming a serious issue for science and policy alike, said lead author Dr. Katy Croff Bell, chair of the Ocean Discovery League and a National Geographic Explorer. - Making informed decisions about resource management and conservation requires a far better understanding of deep-sea ecosystems and the processes occurring there.

To estimate the scale of human knowledge, the researchers analyzed data from around 44,000 deep-sea dives, comparing them with visual observations collected in waters off 120 countries since 1958. While not all dive data is publicly accessible — and the scientists acknowledge that estimates may be off by an order of magnitude — the conclusion remains: visual documentation exists for less than one-thousandth of a percent of the deep-sea floor.

Almost 30% of these visual observations occurred before 1980, meaning the images are in black and white and of low resolution.

Moreover, over 65% of all visual data comes from within 200 nautical miles of just three countries: the United States, Japan, and New Zealand. Due to the high costs of deep-sea exploration, only a few wealthy nations dominate the field. In fact, five countries — the US, Japan, New Zealand, France, and Germany — are responsible for 97% of all deep-sea visual records. This geographical imbalance risks introducing major bias into our understanding of deep-sea ecosystems, the researchers note.

Some types of deep-sea environments — such as submarine canyons and seamount ridges — are relatively well-documented. But vast abyssal plains and many undersea mountains remain poorly explored.

Scientists call for more comprehensive and globally inclusive deep-sea research efforts, arguing that conservation and management should reflect the true scale of the ocean floor. If our understanding of land ecosystems were based on just 0.001% of their area, we would be drawing conclusions about all of Earth’s terrestrial nature using data from a patch the size of a single city — like Houston, Texas.

According to the authors, there is cautious optimism that things may improve, thanks to emerging technologies that are beginning to make deep-sea exploration more feasible and accessible.

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