Study Finds That We've Only Seen 0.001% of Our Deep Seafloor

An image of a seafloor taken from underwater

The ocean covers about 70% of the Earth’s surface, and yet a new study reveals just how little we know about the largest livable space on our planet. Published on May 7 in the journal Science Advances, the report found that humans have seen less than 0.001% of our deep seafloor—an area roughly equivalent to that of Rhode Island.

The deep sea is renowned for being one of the world’s most inaccessible environments, at more than 656 feet below the ocean’s surface. Here, light is sparse and the water frigid, allowing bizarre creatures like the flapjack octopus and anglerfish to thrive in near-complete or total darkness. These ecosystems are equally essential to regulating and maintaining our climate, absorbing about 90% of the world’s excess heat and about 30% of the carbon dioxide that human activities release into the atmosphere. From phytoplankton that produce an estimated 80% of the world’s oxygen to the marine sponges that boast a range of medicinal chemical compounds, the study’s authors share that this incredible biome provides “critical services and resources to humankind.”

Researching the deep sea may be crucial, but it’s also a daunting task. Tools like sonar can certainly reveal the shape of the seafloor, although those maps aren’t nearly as comprehensive or detailed as those produced by cameras, which are far more challenging to plunge that deep into the ocean.

“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,” Katy Croff Bell of the nonprofit Ocean Discovery League, who led the study, told NPR.

For those very reasons, it might not come as a surprise that we’ve explored so little of the deep sea. Even so, the 0.001% statistic is illuminating, proving how much we still have left to discover. To reach such a conclusion, Bell and her team produced a database of about 44,000 records of deep sea activities, starting in 1958 and involving everything from robotic vehicles to human-driven subs.

These efforts have not only been vastly limited in terms of seafloor area, but also in geographical scope. The study determined that a majority of visual observations occurred within 200 nautical miles of the United States, Japan, and New Zealand. These three countries, alongside France and Germany, led nearly all of the expeditions.

“The Indian Ocean is one of the least explored areas,” Bell explains. “Given how little we’ve seen and how biased it is, we can’t really give you a global map of all the habitats of the deep sea, because we just haven’t been to all of them.”

For Time Magazine, Bell added: “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.”

The study comes on the heels of U.S. President Trump’s executive order, signed on April 24, seeking to fast-track deep sea mining in the Pacific Ocean. The move has prompted significant outcry—and anxieties about mining effects on deep sea habitats.

“It’s like clear cutting the forest,” Jeff Watters, VP of external affairs at Ocean Conservancy, told Time. “You’re talking about completely destroying a deep sea bed environment for all intents and purposes on the human scale permanently.”

To learn more about these fascinating findings, read the full study in Science Journal.