Experts are pushing for better bathymetric charts of the ocean floor at a time when, technically, it’s already 100 percent mapped. What’s wrong with today’s maps, and what effects will improvements have?

A bathymetric map of the southern Gulf of California showing the locations of the Pescadero Basin vent site where Adam Soule went on a research expedition in fall 2017. Image Credit: Goffredi et al., 2017

In 1977, the world got its first look at the ocean floor. A map was published, a panoramic painting resulting from roughly two decades of work. It revealed mid-ocean ridges and rifts, features so unprecedented, the scientific community greeted them with skepticism.
Now the world has a better idea of what to expect, in large part due to transformations in ocean-floor cartography. In 2013, for instance, geophysicist David Sandwell used gravitational measurements from satellites to publish a much more detailed map of the entire ocean floor.
People are still mapping, though, and there’s still a push for more efficient mapping technology.
For those outside the scientific fields, the question might be “why?”

The ocean sits on pillows?

The 1977 map is famous for more than its ocean-floor reveal. Geologist and oceanographic cartographer Marie Tharp was a major contributor, bucking the era’s gender roles. Her accomplishments were groundbreaking for women in science, but Tharp’s seafloor revelations had the more immediate effect.
The underwater mountains and valleys she charted were revolutionary. It turns out they also were inaccurate.
Calculations are only as good as their measurements. While Tharp’s calculations were correct, the measurements she used came from mid-20th century sonar.
The result was a very stylized map, according to Scott Ferguson. “When we first started collecting high-resolution seafloor data, people had a very poor understanding of what the bottom of the ocean looked like,” he explained. “They thought the ocean was pillowy: Big, round fluffy stuff was literally what they drew.”
Ferguson is the University of Hawaii’s marine technical services director. Before that, he spent 35 years working on seafloor mapping.
Ferguson said the width of sonar beams used prior to the 1980s produced images unclear by today’s standards. Tharp’s 1977 map revealed mountains and valleys, but the detail it depicted, or its resolution, was poor. Vague maps are problematic, according to Ferguson.

“One reason high-resolution bathymetry is important is that, without maps, we have a very limited understanding of the area we are working in,” he said. “Unless you’ve got a base map, it’s very hard to conduct any research.”
Seafloor charts have improved over the decades, but their level of detail still isn’t good enough for deep-sea researchers. Ferguson says current resolutions are a barrier to research.
Vehicles such as submersibles, remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) explore and sample the ocean floor. Those are difficult tasks if the pilot, whether person or program, doesn’t know where the ocean floor is. They’re also perilous if the vehicle finds the floor before a map does.
The solution is more maps. Research ships and underwater vehicles are equipped with powerful mapping technology. At each step of the downwards journey, a new localized, high-resolution chart is made.
In March 2017, four decades after Tharp’s map, that process was used by CSIRO’s Research Vessel (R/V) Investigator to provide the first detailed view of some of the Antarctic seafloor.
Forty years is a long time, especially when maps are essential for reaching the seafloor “labs” researchers work in. Maps also help scientists characterize regions, and enable improved marine management.

Resolving another world

Riftia, or tube worms, seen during Soule’s recent expedition with E/V Nautilus in the Gulf of California; these worms are part of chemosynthetic communities that rely on chemicals found along cracks within the seafloor. Image Credit: OET/ Nautilus Live

It’s clear ocean-floor maps aren’t as good as they could be, but why do they need to be better? How much does resolution really matter?
Adam Soule works as an associate professor at Woods Hole Oceanographic Institution (WHOI), teaching and researching geology and geophysics.
Like Tharp, Soule is interested in the seafloor’s volcanic and tectonic processes. Today, he studies them at the boundaries Tharp discovered: the mid-ocean ridges and valleys.
Knowing where and what the ridges are doesn’t make it easier to study them. According to the U.S. National Oceanic and Atmospheric Administration (NOAA), the average ocean depth is 2.3 miles, or 12,100 feet. The pressure is roughly 5,402 pounds per square inch at that depth.
It’s a bit of a hostile work environment.
Soule and other researchers rely on machines to tackle the challenge, but technology isn’t efficient if it’s blind. Take Soule’s work in the Gulf of California: He knows there are places in the Gulf where the creation of ocean crust is happening.
Finding those places, though, is easier said than done.
“With satellites, we have produced a map of the entire ocean basin at a resolution of about 1 kilometer or so per pixel. With a map of that scale, you’re able to find large features, like the mid-ocean ridges,” Soule said. “Many of the samples we need, and the observations we need to understand the processes that are going on on the seafloor, are at the scale of meters or even smaller.”
Existing maps got Soule’s ship to the mid-ocean ridge he was interested in. Then he used shipboard technology to create a map for the underwater vehicle. As the vehicle neared the ocean bottom, it, too, created a map, this time for Soule to “see” and study the ocean floor.
It’s a lot of work. Imagine every office employee building their own desk each morning: the world would be a lot less productive.

Next-generation frustration

Repetitive mapping is so routine, it’s part of the next generation’s education. Meghan Jones, for example, considers it a normal part of her work.

Adam Soule installs a camera on the manipulator of ROV Hercules before a dive in Guaymas Basin this November. Image Credit: Nautilus Live/OET

As a geology and geophysics Ph.D. candidate, Jones has studied under Soule. She’s also taken part in several research expeditions with him, including one in August 2015 that revealed the intrinsic value of seafloor maps.
Several institutions collaborated to map around the Galápagos Islands that summer. Jones was focused on tiny underwater volcanoes, but some people were after the charts.
“We provided seafloor maps to NOAA, to aid their evaluation of tsunami hazards, and to the Galapagos National Park, to refine zoning within the Galapagos Marine Protected Area,” she wrote in an email. “There was also an exciting amount of interest from the public, made possible by news articles and social media.”

The bathymetry comparison above is from an area south of Floreana Island, Galápagos. The top image is the area’s bathymetry before the August 2015 expedition, mapped to a resolution of about 1 km per pixel. The bottom image shows bathymetry mapped during the expedition with a resolution of 10 meters per pixel, two orders of magnitude difference. Image Credit: Adam Soule, WHOI, Dalio Explore Fund

Benefits

In 2003, scientists reached a major milestone: they mapped the unique pattern making up the human race. The milestone’s importance situated it not just in the scientific realm, but the public one as well.
The Human Genome Project owes a debt to the ocean floor, though. Its efforts were possible because of deep-sea research, specifically the discovery of a hot spring microbe whose enzyme allowed for DNA replication.
It’s a story Peter Girguis, Harvard professor of organismic and evolutionary biology, uses to connect the public to the seafloor.  
Girguis is a deep-sea biologist and biogeochemist, meaning his focus is on how microbes survive in that environment and how they adapt to its changes. Close scrutiny has revealed some microbes, including ones he researches, produce methane.
“In the context of my research, the work we have done has provided new insight in how we might be able to produce biofuel at a large scale, based on organisms that we find in deep-sea hot springs,” he said.
The public’s love of adventure gives Girguis another way to connect. The idea of life on other planets? He credits the concept to discovering life where it shouldn’t have been on the ocean floor.
“We really thought the biodiversity and productivity of our planet relied on sunlight,” he said. “We didn’t think a planet could support life unless it was the exact right place for a star to illuminate it and kept it just-so-warm.
“These ecosystems in the deep sea shattered these notions. That’s why people are hearing biologists, more and more, talk about life on other planets: It finally dawned on us that there could be entire organisms living on other worlds, and they don’t need the sun.”
All of these things, Girguis said, are ways deep-sea research is reaching out to the public. Right now, that promising research is literally groping around in the dark. “The maps cannot resolve, or ‘see,’ smaller than a city block,” he said. “The way I think of it is, I give you directions to visit me at Harvard, and very best I can do is lead you to a city block. Now find my office.
“Oh, and it’s midnight with a power outage: the deep sea has no sunlight.”

This octopus peeking out from rocks in the Gulf of California’s North Guaymas Basin in October is one of the top predators in a hydrothermal vent system that reaches down to microbes. Image Credit: Nautilus Live

The motivation

The knowledge born from pure research, or the observation of the universe with no assumptions or predictions, motivates a good chunk of deep-sea specialists.
Soule is one example. “We need to know the ocean,” he said. “The level of mapping we have right now is not sufficient to know where resources are located, where animals are located and where kind of the key scientific questions can be answered.”
This kind of information is missing today, but it doesn’t have to be. Current technologies make pure research possible: An ROV or an AUV can work around the clock, braving environments that just aren’t safe for humans.
Developing more efficient technologies could make the work more economically feasible.
“In the grand scheme of things, science compared to community benefit is a dirt-cheap investment,” Girguis said. “We have to invest sufficiently in science because, when we do that, the payoffs are extraordinary.”
For Girguis, not stumbling around in the dark is great motivation for high-resolution maps. It’s not the only motivation, though. “Without the maps of our underwater land, we lack the very basic, most rudimentary information to make the best decision as a nation.”
Jenny Gessaman is a rural Montana journalist passionate about delivering information in a relatable way. Follow Gessaman on Twitter @MTJournalist.

AUVs and ROVs help shed light on the bottom of the oceans, and discoveries like this shrimp perched inside a glass sponge might inspire some to continue mapping efforts. Image Credit: NOAA Office of Ocean Exploration and Research, Discovering the Deep: Exploring Remote Pacific MPAs