Looking at Google Maps, it may seem as if every last corner of the planet has already been subjected to topographical surveys. But what lies beneath the ocean surface remains largely hidden from the view of orbiting satellites.
That’s because radar signals can’t penetrate water. So while commercial satellites provide a resolution of about 30 centimeters per pixel of the Earth’s surface, ocean images are much rougher, with a resolution of around just 5 to 8 kilometers (3-5 miles) per pixel.
Only about 20% of the ocean floor has been surveyed so far with echo sounding. But Seabed 2030, a joint project between the and the private Nippon Foundation, aims to map the entire ocean floor by the end of this decade.
Ocean depths hold ‘entire worlds’
“The covers 71% of the planet, so it’s just vast, incomprehensibly vast,” said Laura Trethewey, a Canadian environmental journalist and author of “The Deepest Map: The High-Stakes Race to Chart the World’s Oceans,” published in 2023.
“There’s just no terrestrial equivalent, which is why we so often compare the ocean to the moon or outer space. There’s nowhere else on land that comes close to the ocean in terms of size,” she added, pointing out that both the moon and Mars have been more thoroughly mapped than the ocean floor.
“We stretch for the stars and dream of building new perfect societies on Mars. But I would point out that we have this otherworldly space right here on Earth that we haven’t finished exploring yet.”
To explore the underwater universe, acoustic sound waves are emitted in a fan-like pattern from ships, diving robots and submarines in various directions toward the seafloor. The time it takes for these signals to travel to the bottom and back is measured individually for each sound wave, from which the depth is calculated. The deeper the sound, the deeper the sea.
Surveying with multibeam echo sounding provides topographic maps, three-dimensional models and terrain profiles even for very great depths. “There are entire worlds that we’re missing out on right here on Earth — undiscovered mountains and canyons, animals unknown to science and just huge amounts of data and discoveries that are still out there waiting for us,” said Trethewey.
In light of , researching the seabed could also provide important information about what the future could hold.
“A lot of the seafloor used to be land. After the last ice age, melting glaciers released water that covered continental shelves that are equal to the size of South America. So there’s a whole other continent down there, another lost Atlantis, that could hold insight into how past human societies navigated sea level rise and what we might do facing the same problem in the future,” said Trethewey.
“Making the map is the first step in making that future a reality.”
An ambitious project
Seabed 2030 will likely fall short of its ambitious goal, however. The oceans are simply too large and the ships and sonar equipment needed are lacking — not to mention the delays due to the and a waning political motivation.
“Back when the project launched in 2017, the world was a less fractured place, geopolitically. We live in a more unstable time now and governments are more suspicious and less willing to share maps,” said Trethewey, adding that technology isn’t the issue as it has existed for decades.
Organizers have tried in vain to “make up for any shortfalls with innovations like drones and crowdsourcing and recruiting super yachts and cruise ships to map the seafloor,” she said.
Major ‘push to exploit the deep sea’
But the fact remains that deep-sea exploration poses an extreme challenge for both humans and equipment. Adverse conditions at sea require expedition costs of around $50,000 (€43,000) a day, said Trethewey, “which means governments and businesses often need a good incentive to map, usually for resources, infrastructure or national security interests.”
Seabed 2030 has estimated that the cost of reaching its goal will be between $3 billion and $4 billion (€2.5 billion to €3.4 billion) —roughly equivalent to the NASA Mars mission that began in 2020 and included landing a rover on the planet.
One downside of success could be that more complete mapping would significantly accelerate the , however. “When people think of maps, they often think of . And they’re not wrong. Right now there’s a big push to exploit the deep sea and open the first commercial mines in international waters,” said Trethewey.
But she hopes that mapping will be used primarily for science and conservation, as the international community agreed to do after the complete mapping of with the Antarctic Treaty in 1959, which protected the continent for scientific purposes for 60 years.
Still, strict regulations are unlikely to protect the deep sea as effectively as ignorance and inaccessibility.
“Nearly two-thirds of the ocean and almost half the surface of the planet fall in what’s called international waters, so no country or person has ownership rights over it. This unclear legal status is the major reason why the international ocean is mostly unmonitored and unregulated, and why it’s so hard to tackle crime at sea, whether it’s or drug trafficking,” said Trethewey.
“Stricter ocean governance would be welcome, but what’s perhaps more important are money and political will,” she added. “The ocean is vast, incomprehensibly vast […] and without money to fund monitoring and enforcement at sea, more rules are largely meaningless.”
This article was originally written in German.
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