Mapping Greenland’s fjords and glaciers: three ice tongues and the secrets of the seafloor

 

From ESRI by Dr. Dawn Wright

Bathymetric mapping of remote Greenland fjords reveals critical insights into glacier dynamics, ocean interactions, and climate change impacts shaping the Arctic environment.

Key Takeaways

• Maps of Greenland’s fjords reveal underwater features that shape glacier behavior.
• Detailed maps show why some glaciers are melting faster.
• Climate models and sea level rise predictions clarify glacier-ocean interactions in the warming Arctic.

The Swedish icebreaker Oden set a course in summer 2024 through the Nares Strait, a narrow, ice-choked waterway that cleaves Greenland from the Canadian Arctic.
The ship was headed for Greenland’s Victoria Fjord, near the world’s northernmost land point—a place so remote, no known ship had ever explored it.

 

 Victoria Fjord in the north of Greenland with the GeoGarage platform (DGA nautical raster chart)

 

Oden carried a group of 40 scientists who study the Arctic.
It marked the third such trip to Greenland fjords since 2015, all organized by the Swedish Polar Research Secretariat.
But none had yet attempted to penetrate this far into the thick summer sea ice.

A diesel-powered behemoth, Oden spreads 107 meters from stem to stern and rises six stories above the waterline.
The trip would take them farther into the Last Ice Area (LIA) than icebreaker captains like to go.
A few of the scientists calculated 20 percent odds of reaching Victoria without turning back.

Onboard, two experts in marine geology and geophysics—Martin Jakobsson, of Stockholm University, and Larry Mayer, of the University of New Hampshire—led a team of mapmakers.
They planned to use a geographic information system (GIS) to map the fjord’s seafloor, 400 meters below the ice.

The maps would support the work of all scientists on the expedition and potentially reveal crucial secrets about the rising oceans.

Icy Spatial Context

Mapping underwater topography requires the creation of a bathymetry map, comparable to a topographic map of land.
Oden’s acoustic tools—echo sounders for seafloor depth and shape, Doppler profiles for currents, sub-bottom profilers for sediment history—feed the maps with all the details they need.

In turn, the maps provide what Mayer, in a mid-voyage dispatch, called “spatial context” for the biological, oceanographic, and geochemical data being gathered.

The maps also had a more immediate application.
Victoria Fjord had been observed through satellite imagery, but never closely mapped at the source.

 No detailed ENC in the area

 

No known nautical charts existed.
The lack of exact knowledge about depth and the presence of small islands, along with the constant presence of sea ice, called for slow movement and extreme caution.

The technology was “essential for determining whether Oden can safely navigate in the uncharted waters in the area,” Mayer wrote.

Ten days and 227 nautical miles later, Oden reached Victoria.
The maps made there confirmed one theory—and uncovered an unsolved mystery.

 

The Swedish icebreaker Oden, a 107-meter-long diesel-powered research vessel, carried 40 scientists through the ice-choked Lincoln Sea to map fjords no ship had explored before.

Modeling the Rising Seas

To understand sea level rise, scientists build predictive models.
Planners and policymakers use the models to see where and when municipalities will require evacuations, and which coastlines can be protected by seawalls.

The models affect where houses will be built, and how critical infrastructure will be protected.
They also strengthen economic predictions, such as quantifying risks for insurers and underwriters.
These decisions have broad implications, directly impacting much of the global population.
One billion people worldwide live within 10 kilometers of a coastline.
In the US alone, 140 million live in coastal counties.

Without good knowledge of the melting glaciers, predictive sea level models will be inaccurate by between 15 and 20 percent.
And because some of the changes are happening below the ocean’s surface, satellite imagery is not enough.

Scientists have no choice but to make slow voyages through the ice, using GIS to make bathymetric maps.
The future of sea level modeling demands it.

• 

    A Greenland glacier meets the coast, its fractured face revealing the stresses of constant motion.
As snowpack accrues, gravity slowly carries glaciers toward the sea, where fissures form and ice chunks calve into the water—a natural process now accelerated by warming temperatures and meltwater running beneath the ice.
  

 All Eyes on the Ice Sheet

Around the time of the first of the three Oden voyages, in 2015, the melting of the Greenland ice sheet—a single mass covering 80 percent of the island—was determined to be the biggest driver of sea level rise.
It remains so today.

Greenland’s ice sheet includes at least 215 glaciers that terminate at the coastline.
The sheer mass of these glaciers leads to their enormous kinetic force.
Over time, as snowpack accrues, a glacier slowly turns over on itself, letting gravity carry it to the coast.
Imagine a blob of very cold honey on an incline, slowly succumbing to gravity.

This constant motion puts stress on the glacier, causing fissures to form.
When the fissures ripple outward, compromising the glacier’s stability, ice chunks break off the front and into the ocean—a process called calving.

Every year, Greenland’s coastal glaciers calve around 450 gigatons of ice into the ocean, the equivalent mass of the world’s tallest building, Dubai’s Burj Khalifa, every 10 hours.

Absent the warming climate, calving serves a natural purpose, helping a glacier maintain equilibrium over time as its overall mass increases.
Today, the melting ice sheet is causing water to run underneath glaciers, accelerating destabilization and increasing the rate of calving.

 

The Mystery of Northern Greenland’s Glaciers

Most of the calving currently comes from the glaciers on Greenland’s east, west, and south coasts.
But there is an important caveat.
The northern glaciers drain a total catchment area that is disproportionately large, compared to the giants on the other coasts.
And drainage has been a slower process than elsewhere in Greenland.

It is the fjords that have slowed calving in the north.
Glaciers that drain into fjords develop floating ice tongues that extend out from the water’s edge.
Most are between 1 and 40 kilometers long, with a width between 15 and 30 kilometers.

Ice tongues anchor themselves to local topography, such as islands and the sides of the fjords.
An ice tongue buttresses its glacier, adding structural integrity that slows down the rate of calving.

For now, northern ice tongues are slowing the drainage.
But questions remain about how exactly they’re doing this—and how long they’ll continue, as warmer ocean waters eat away at them.

 

The Mystery of Northern Greenland’s Glaciers

Most of the calving currently comes from the glaciers on Greenland’s east, west, and south coasts.
But there is an important caveat.
The northern glaciers drain a total catchment area that is disproportionately large, compared to the giants on the other coasts.
And drainage has been a slower process than elsewhere in Greenland.

It is the fjords that have slowed calving in the north.
Glaciers that drain into fjords develop floating ice tongues that extend out from the water’s edge.
Most are between 1 and 40 kilometers long, with a width between 15 and 30 kilometers.

Ice tongues anchor themselves to local topography, such as islands and the sides of the fjords.
An ice tongue buttresses its glacier, adding structural integrity that slows down the rate of calving.

For now, northern ice tongues are slowing the drainage.

Ice mélange—the chaotic mix of icebergs, sea ice, and snow shed by calving glaciers—chokes Greenland's coastal waters.
Every year, the island's 215 coastal glaciers calve roughly 450 gigatons of ice into the ocean

 

The Vanishing Ice Tongue

 

Each of Oden’s voyages has targeted one fjord and the glacier it fronts.
Each journey has answered a crucial question, while raising another that the next voyage has tried to answer.

The destination of Oden’s first voyage with the Arctic scientists was the Petermann Fjord, which fronts its namesake glacier.
A few years prior, satellite imagery had revealed that the glacier had lost a big chunk of its ice tongue.

Scientists had theorized that warm water from the Atlantic Ocean was flowing up to the Arctic.
When the Oden team added oceanographic data to the bathymetry, this revealed that warm water was indeed entering the fjord.
The warming ocean was melting Petermann’s ice tongue.
 

 

 Arctic researchers navigate ice-choked waters by inflatable boat—a reminder that mapping the seabed beneath Greenland's fjords often requires getting dangerously close to the ice.

 

The Growing Ice Tongue

There was just one problem with this conclusion.
Further up the Lincoln Sea, something very different was happening to the Ryder Glacier, which drains at Sherard Osborn Fjord, the destination for Oden’s second Lincoln Sea voyage, in 2019.

Satellite imagery of the Ryder Glacier revealed that its ice tongue was not only intact—it was stable and sometimes even growing.

This was a mystery, and it called into question the warm water theory.
If warm water from the Atlantic could reach Petermann, what was stopping it from getting to Sherard Osborn?

The maps solved the mystery.

Like many fjords, Petermann contains a sill, a submerged ridge that can restrict the flow of water between fjord and ocean.
Petermann’s outer sill sits at 440 meters below the surface, deep enough to allow the warm water to flow over it and enter the fjord.

Sherard Osborn also has an outer sill deep enough for warm water to enter.
But an inner sill, just 200 meters down, acts as a second barrier—shallow enough to block the warm water from reaching the glacier.

“And so, there was the proof,” Mayer said.

The warm water theory held.

“Like a Nuclear Bomb Had Gone Off”

Five years later, the 2024 voyage initially sowed new doubt about the sill theory.

When Oden beat the odds and reached Victoria, it was soon apparent that only about the first one-third of the fjord was accessible.
The team could access just part of the fjord’s C.
H.
Ostenfeld Glacier.
Beyond that, huge icebergs blocked the way.

So they hung an echosounder from a cable attached to a helicopter launched from Oden.
The pilot flew across the icebergs, dipping low to drop in the echo sounder wherever open water appeared.

They gathered bathymetry from just 19 spots.
But along with the good data they had already recorded, it was enough for a decent map.

Still, the results were troubling.
The first sounding showed a shallow sill on the seabed.
Unlike at Sherard Osborn, the shallow sill was apparently not protecting the ice tongue.

But then they got measurements on the other side of the fjord and found a deep passage allowing warm water to go all the way to the glacier.
That was what was melting the ice tongue.

The shallow sill theory of ice tongue protection still held true.

The scientists hoped to get at least a cursory view of the glacier’s face—the place where it met the fjord.
Two team members flew over it in the helicopter.

The faces of the Petermann and Ryder Glaciers had appeared smooth and sheer.
C.
H.
Ostenfeld Glacier looked like it was collapsing into the water.
Wherever they looked, they saw ice mélange, the chaotic mixture of icebergs, sea ice, and snow created when a glacier sheds large icebergs.

“It looked like a nuclear bomb had gone off,” Mayer said.

Warm water by itself could not cause this level of destruction.
“We think it has something to do with the combination of warm water intrusion and bedrock slopes,” Mayer said.

Once again, the solving of one scientific mystery raised another—a puzzle that future bathymetry maps will try to solve.

The Mapping Continues

In 2025, Oden returned to the Arctic—this time joined by a Canadian icebreaker, CCGS Louis S.
St-Laurent.

The expanded mission reflects how quickly the stakes have risen.
The bathymetric mapping now serves dual purposes: advancing climate science and supporting territorial claims under the UN Convention on the Law of the Sea.

As the Arctic continues to thaw, opening new shipping routes and exposing untapped resources, the maps take on geopolitical weight.
The collaboration brings together scientific inquiry, Indigenous sovereignty (Inuit observers regularly sail aboard Canadian vessels), and strategic interests—all guided by what the seafloor reveals.

The warm water still surges north.
The ice tongues are still retreating.
And now, with two ships cutting through thinning ice, the race is on to map what remains before it’s gone.

 

Links :

• GeoGarage blog : Polarstern expedition to study the changing Weddell Sea 

From hydrography to hydrospatial intelligence – the liability paradox of s-100 data model

From Pulse by Sanjeev Sharma COO at Tridel Technologies

 

A Grounding That Wasn’t a Single Failure

The vessel was inbound on a routine approach, navigating a familiar channel under seemingly benign conditions.
The bridge team relied on an integrated navigation system displaying high-resolution bathymetry, real-time tidal data, and predictive under-keel clearance (UKC) calculations.
Yet, within moments, the vessel touched bottom.
Subsequent investigation revealed no single catastrophic failure, but rather a chain of small discrepancies: a slightly outdated bathymetric grid, a delayed tidal update, and a decision-support system that fused both into an overly optimistic UKC margin.
In the era of the International Hydrographic Organization S-100 data framework, this is not a hypothetical scenario—it is an emerging reality.
And it raises a fundamental question: when navigation becomes a product of multiple data sources and algorithms, who owns the outcome—and who is accountable when it fails?

Redefining the “Product ownership” and “Product” in an S-100 World

Traditionally, hydrographic product ownership was clear and singular.
National Hydrographic Offices (HOs) produced official Electronic Navigational Charts (ENCs), validated their contents, and stood as the authoritative source for safe navigation.
Liability, while rarely tested in courts, was implicitly anchored in this centralized model of control and responsibility.
However, S-100 dismantles this simplicity.
It replaces a monolithic product with a modular, interoperable data ecosystem, where the “chart” is no longer a standalone artifact but a dynamic aggregation of datasets, services, and system-generated outputs.
In doing so, it transforms not only how navigation data is delivered, but also how ownership and liability must be understood.

At the heart of the issue lies a definitional challenge: what constitutes the “product” in an S-100 environment?

Is it the individual dataset—such as an S-102 bathymetric surface or an S-104 tidal stream?

Is it the real-time service delivering continuous environmental updates?

Or is it the final, fused representation on an ECDIS or autonomous navigation system, where multiple inputs are algorithmically processed into a single navigational recommendation?

Each layer has its own creator, its own update cycle, and its own uncertainty profile.
Yet to the mariner, these distinctions are invisible.
What is perceived is a unified, authoritative output—an expectation inherited from the S-57 era, but increasingly misaligned with the distributed nature of S-100.

This fragmentation gives rise to a complex and potentially problematic data supply chain.
Hydrographic offices continue to provide foundational datasets, but they are now joined by port authorities supplying high-resolution local surveys, meteorological agencies contributing environmental overlays, private firms generating commercially driven bathymetric updates, and sensor networks streaming real-time conditions.
Value-added service providers further integrate and process this data into decision-support tools.
The result is a federated system of interdependent contributors, none of whom individually control the full navigational picture.
Ownership, in this context, becomes diffuse—shared across actors who may never directly interact, yet whose data converges at the point of use.

The Liability Paradox of S-100

It is within this convergence that the liability paradox of S-100 emerges.
Authority remains expected, but control is distributed.
Responsibility is assumed, but ownership is fragmented.
In the event of an incident, such as a grounding, attributing fault becomes inherently complex.
Was the bathymetric data insufficiently updated? Did the tidal service fail to deliver timely information? Did the integration platform misinterpret input data? Or did the vessel operator place undue reliance on automated outputs? Existing legal and regulatory frameworks offer limited guidance for such scenarios, as they were conceived in an era where data provenance was singular and product boundaries were clearly defined.

Hydrographic Offices: Authority Without Full Control

The Hydrographic Offices find themselves at the center of this paradox.
While their traditional role as sole data producers is evolving, their position as trusted authorities persists.
Mariners and regulators alike continue to associate Hydrographic Offices with the integrity of navigational information, regardless of its source.
This creates an asymmetry: hydrographic offices may no longer control all contributing data, yet they remain implicitly accountable for the overall reliability of the navigational environment.
The challenge, therefore, is not merely technical, but institutional—how to redefine authority in a system where control is inherently shared.

Rethinking Liability: Toward a Certified Data Ecosystem

A critical step toward resolving this challenge lies in the concept of data provenance and traceability.
In an S-100 ecosystem, every dataset must carry with it a transparent lineage: who produced it, when it was last updated, what are its accuracy parameters, and how it has been transformed or integrated.
Such metadata is not simply informational; it is foundational to accountability.
Without it, assigning responsibility in the event of failure becomes speculative at best.
With it, navigation data evolves into a form of auditable digital evidence, enabling clearer attribution of both value and fault.

From a governance perspective, several models for product ownership and liability can be envisioned.

1. The legacy model of centralized liability, where hydrographic offices bear full responsibility, is increasingly untenable in a multi-source environment.
2. A fully distributed model—where each data provider is independently liable—risks creating confusion and eroding user trust.
3. Certified data ecosystem - A more balanced approach lies in the development of a certified data ecosystem, wherein hydrographic offices transition from sole producers to validators and certifiers of data quality.
   In this model, third-party datasets are integrated into the navigational framework only after meeting defined standards, and liability is structured across the data chain rather than concentrated at a single point.

Regulatory Imperatives in a Multi-Source Data World

The role of the International Maritime Organization becomes critical in this transition.
As the custodian of maritime safety regulations, the IMO must address the implications of multi-source data environments within frameworks such as SOLAS and the e-navigation strategy.
This includes defining what constitutes “official data” in an S-100 context, establishing expectations for data integrity and availability, and clarifying the responsibilities of ship operators when relying on integrated digital systems.
Without such regulatory alignment, the legal ambiguity surrounding S-100 could hinder its adoption and undermine confidence in its capabilities.

Implications for Mariners: The Rise of Data Literacy

For the mariner, these complexities must remain largely invisible, yet their implications are profound.
The integration of multiple data sources introduces varying levels of confidence and potential inconsistency, even as systems present a seamless interface.
This places new demands on both technology and training.
Bridge systems must evolve to communicate not just information, but uncertainty and data quality, while mariners must develop a form of data literacy that allows them to critically interpret system outputs rather than accept them at face value.

Concluding Thoughts - Who Owns Truth at Sea?

Ultimately, the question of product ownership in the S-100 era is inseparable from the broader evolution of hydrography itself.
As the discipline moves toward hydrospatial intelligence, the notion of a static, owned product gives way to a dynamic, shared service.
In this new paradigm, ownership is less about possession and more about accountability within a networked system.
Ensuring that this accountability is clearly defined, fairly distributed, and transparently communicated will be essential to realizing the full potential of S-100.

The grounding incident that opens this discussion is not merely a cautionary tale—it is a signal.
A signal that as navigation becomes smarter, faster, and more interconnected, the frameworks that underpin trust must evolve accordingly.
Because in the end, the success of S-100 will not be measured solely by the sophistication of its data models, but by the confidence with which mariners can rely on the information they receive—and the clarity with which responsibility is assigned when that confidence is tested.

Links :

• Hydro : How the S-100 framework can enable true autonomy for USVs
• IHO : The S-100 framework is now operational 
• Baltic : Guidance towards harmonised development of S-100 products in the Baltic Sea Region 
• Pulse : Charting Strategy in the S-100 Era

Polarstern expedition to study the changing Weddell Sea

The research is taking place at a critical time, when the Antarctic climate system may be entering a phase of accelerated sea ice loss and increasing ocean warming.

(Image courtesy: Ilka Peeken)

From Hydro

Until early April, a multidisciplinary international research team will investigate the northwestern region of the Weddell Sea to study rapid sea-ice and ecosystem changes.

 

Weddell Sea in the GeoGarage platform (UKHO nautical raster chart)

 

The research vessel Polarstern recently departed from Punta Arenas (Chile), marking the commencement of the Summer Weddell Sea Outflow Study (SWOS) international expedition. 

The expedition is intended to make decisive contributions to understanding a key area of the Antarctic ice-ocean system at a time of a profound transition whose effects extend far beyond Antarctica.

For a long time, the sea ice extent in Antarctica was observed to be relatively stable – unlike in the Arctic, where the summer ice extent has shrunk by around 12% per decade since satellite records began in 1979. 

Since around 2017, however, significant changes have been observed in the northwestern Weddell Sea: the summer sea ice extent has declined sharply, presumably as a result of warmer surface water.

The Weddell Sea is an area of central importance for the global climate and ocean system, but one that can only be explored on site by research icebreakers such as the Polarstern due to challenging sea ice conditions. 

“The aim of SWOS is to investigate why sea ice in Antarctica has declined so sharply in recent years and how this is impacting the ecosystem,” states Prof Dr Christian Haas from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), who is leading the current Polarsternexpedition.

At the same time, the sea ice physicist reports that an unexpected situation has arisen this year: “Ironically, there is currently an unusually large amount of ice in the western Weddell Sea, which may be a normal fluctuation without contradicting the trend. 

Consequently, it remains to be seen whether we will be able to penetrate deep into the south as planned – meaning that we will adapt our questions to the prevailing conditions en route and develop them accordingly.”

Global significance for oceans

The northwestern Weddell Sea is situated along the northward-flowing Weddell Gyre, which transports large quantities of different water masses and thick sea ice into the world’s oceans. 

In addition, icebergs calving from the ice shelf carry nutrients from the Antarctic continent into the ocean, where they impact on biogeochemical cycles. 

The region includes a deep shelf sea and the Larsen C Ice Shelf, the second-largest ice shelf in the Weddell Sea.

In spite of its global significance, actual knowledge of the Larsen Ice Shelf is patchy due to the year-round ice cover, often multi-year sea ice and the extreme weather conditions making it difficult to access. 

“It is currently unclear whether we will be able to reach the vicinity of the Larsen C Ice Shelf as planned,” says AWI Marine Biologist Dr Ilka Peeken, co-leader of the expedition. 

Since the northern part of the working area is less open than in previous years, the route planning will have to be adjusted flexibly. 

Nevertheless, Peeken adds, the expedition is a rare opportunity to penetrate a region that has hardly been studied directly to date.

 

The Polarstern in the western Weddell Sea. 

(Image courtesy: Ilka Peeken)

Observations from seabed to atmosphere

The SWOS expedition aims to collect comprehensive observations for the first time from the seabed to the atmosphere along the northwestern Weddell Sea continental slope, on the shelf and in the vicinity of the Larsen C Ice Shelf. 

A wide range of modern and conventional measurement systems are being deployed, including helicopters to measure sea ice thickness, microstructure probes, CTD rosettes, various trawls and bottom sampling and observation devices, as well as autonomous platforms.

The focus is on the interactions between sea ice, ice shelves and the ocean, as well as their impacts on hydrography, nutrient balance and carbon fluxes. 

The research team is recording ecological processes in the ice and on the seabed, as well as ecological gradients depending on sea ice conditions. 

In addition, the regional sea ice thickness distribution and snow properties will be measured, water masses characterized and exchange processes between the shallow shelf and deep-sea basins investigated.

Need for in-situ assessment

“It is not possible to answer many of our questions by satellites alone,” explains Haas. “We need in-situ observations to understand the state of the sea ice, the currents and the biological communities in the water and on the seabed – as well as to be able to assess whether the sea ice could possibly disappear entirely in the near future.”

The results will be incorporated into ongoing long-term studies, while serving as future projections of the Antarctic system and thereby contributing to the further development of Earth system models. 

The collected data will also be used to improve satellite-based sea ice observations.

Critical time for Antarctic climate system

The research is taking place at a critical time, when the Antarctic climate system may be entering a phase of accelerated sea ice loss and increasing ocean warming. 

“We are operating in a region that has been shaped by the earlier ice shelf collapses of Larsen A and B, as well as recent changes to Larsen C,” says Peeken. 

“It is precisely under these conditions that we have the opportunity to obtain key data on biodiversity changes, ocean currents and sea ice conditions in the Weddell Sea.”

“I am very much looking forward to investigating the extent to which the ice in the northwestern Weddell Sea has changed. I first visited the region over 30 years ago, and seven years ago I was there for the last time with the Polarstern when the sea ice began to change,” recalls Haas.

For Peeken, the close interconnection between the disciplines is the most exciting aspect of the expedition: “Although this region is one of the most inhospitable on Earth, it is teeming with life. Investigating the contribution of the sea ice ecosystem to the carbon cycle is a particular highlight for me.”

Upon concluding the expedition, the Polarstern will embark on its return journey across the Atlantic. The voyage will be used for student training and is scheduled to wind up in Bremerhaven in mid-May.

Links :

• Download the Polarstern app to follow the Polarstern’s route and find out news from on board.
• Children can post their questions for sea ice physicist Dr Stefanie Arndt and oceanographer Dr Sandra Tippenhauer here: Come on board!
• Phys : Polarstern heads to the Weddell Sea to probe Antarctica's sharp sea ice drop 

Katy Croff Bell is making a visual treasure map of the deep sea

Composite satellite visualizations of the Earth.
National Geographic Explorer Katy Croff Bell has created a new interactive globe that pinpoints 10,000 unexplored deep-sea sites, offering scientists a roadmap to a vast seafloor humans have barely seen.
RETO STÖCKLI/NASA/NOA

From National Geographic by Nicholas St.Fleur

 
We’ve barely explored the ocean’s floor.
This new 3D map offers 10,000 new spots to look at next. 

Reporting in this article is presented by the National Geographic Society in partnership with Rolex under the National Geographic and Rolex Perpetual Planet Ocean Expeditions.
After years of deep-sea sleuthing, National Geographic Explorer Katy Croff Bell has created a treasure map.
It’s not drawn on tattered parchment, nor is there one big ‘X’ that marks the spot.
Rather, it’s a 3D interactive globe with thousands of dots speckled across the seas.

For Bell, each point is a coordinate to collect something more valuable than gold, jewels, or doubloons: a rare glimpse of the bottom of the ocean.
On Wednesday, the Ocean Discovery League, where Bell is founder and president, announced the release of the map, which highlights 10,000 target spots on the global deep seafloor, or underwater areas below 650 feet.
Bell’s team simultaneously published the research methods used to construct the map in the journal Science Advances.

“I’m hoping it’s going to be a new era for deep-sea exploration and discovery,” says Bell.

The work is a continuation of a study Bell and her team published in 2025 that estimated only 0.001 percent of the seafloor—an area she likens to the size of Rhode Island—has ever been seen by human eyes.
Now, in addition to the digital map, Bell is helping develop a pioneering deep-submergence lander (called the Deep Ocean Research and Imaging System, or DORIS) that will allow researchers to quickly and affordably survey unseen spots on the ocean floor, as National Geographic reported last year.

The team’s goal in releasing the interactive map and making it widely available is to provide other researchers and maritime explorers with a guide to never-before-seen seafloor locations.
At these sites, researchers can then deploy submersibles, remote underwater vehicles, or the organization’s own low-cost deep-sea DORIS tool to record video of what lies below in hopes of expanding our knowledge of the ocean floor.

“Often as deep-sea scientists, sampling is done per chance or per historical sampling done by others or biased towards interesting environments,” says National Geographic Explorer Sheena Talma, a marine biologist from Seychelles who researches fish in the Southwest Indian Ocean, but was not involved in the paper.
She says she would use both the new map and DORIS in her work if the opportunity arrived and it aligned with her research goals.

“Having a point on a map really helps when you do not know where to start,” she says

https://global-deep-sea-exploration-goals.vercel.app

 

Diving through data

To create their map of 10,000 points, Bell and her team first had to construct a database of the known locations where people have dived.
That required combing through the historical record and scientific publications, as well as sending emails and making cold calls to deep-sea researchers worldwide and requesting the geolocations of their dives.
The dataset they made spans from 1958 to 2024 and includes nearly 44,000 deep-sea dives.

When they probed the data, Bell and her team found that most of those dives represented only 12,000 unique locations, most of which were clustered around high-income countries such as the United States, Japan, and New Zealand.
If each of the 10,000 points on the map is explored, “we're going to almost double the number of unique locations around the world” that have been seen, Bell says.

For Kristen Johannes, a project scientist at the University of California, Santa Barbara, and lead author of the paper, the map is a puzzle she’s excited to solve with collaborators around the globe.

(In the ocean's 'twilight zone,' divers risk their lives in search of mysteries)

“For the last 50 or 70 years, we've been doing the edge pieces around our countries, in jurisdictional, exclusive economic zones,” says Johannes, who previously worked at Ocean Discovery League.
“But now we really need to start filling in the middle of that picture and learning about the complete set of possible environments, organisms, and ecosystems in our deep ocean."

A total of 11,267 unique historical seafloor observation locations (orange) are primarily concentrated within 200 nautical miles of the coastlines of high-income countries.

The 10,000 new target seafloor observation locations (yellow) proposed by Katy Croff Bell, which she says provide a representative view of the global deep seafloor
OCEAN DISCOVERY LEAGUE

Making the map

 
The team wanted the spots they highlighted to provide a mosaic of the full diversity of the vast and wondrous deep-ocean environment.
So after identifying the locations of previous deep-sea dives, they next had to determine the metrics by which they would evaluate the rest of the ocean.
They came up with four: seafloor depth, seafloor shape, seafloor composition, and food availability.

Seafloor depth means the distance from the ocean surface to the bottom.
Seafloor shape is the geomorphology of the site—for example, if it has seamounts, abyssal plains, or trenches.
Seafloor composition refers to what the seafloor is made of, including the types of sediments and features it contains, such as hard crusts, hydrothermal vents, and “ooze,” which is sediment composed in part of the skeletons of dead microscopic marine animals.
Food availability refers to the amount of food remnants originating on the surface—like phytoplankton, a whale fall, or poop—that eventually reach the bottom of the ocean.

They also wanted the map’s locations to focus on areas not clustered around high-income countries, to correct for the historical biases of previous dives; instead, they highlighted often-overlooked or under-resourced places for deep-sea research, such as The Gambia, Sri Lanka, and Trinidad and Tobago.

The 10,000 Global Deep Sea Exploration Goal locations are visualized on six views of a three-dimensional surface of Earth: (A) Arctic Ocean, (B) Atlantic Ocean, (C) Indian Ocean, (D) Western Pacific Ocean, (E) Eastern Pacific Ocean, and (F) Southern Ocean.
OCEAN DISCOVERY LEAGUE

 

“The last thing we want to do is put together a program that only elite research institutions can participate in,” says Johannes.
"What we're hoping to do here is not only provide the kind of 'carrot' of places to collectively explore, but also provide the means, the knowledge, and the skills that are needed for everyone to engage in exploring."

They also decided not to feature famous shipwrecks like the Titanic that have already been visited, or hubs for marine research like Monterey Bay in California.

 

Links :

• Sciences Advances : How little we’ve seen: A visual coverage estimate of the deep seafloor
• Ocean Discovery League blog 

Longitude by Dava Sobel

Anyone alive in the eighteeth century would have known that "the logitude problem" was the thorniest scientific dilemma of the day--and had been for centuries.

Lacking the ability to measure their longitude, sailors throughout the great ages of exploration had been literally lost at sea as soon as they lost sight of land.

Thousands of lives, and the increasing fortunes of nations, hung on a resolution.
The scientific establishment of Europe--from Galileo to Sir Issac Newton--had mapped the heavens in both hemispheres in its certain pursuit of a celestial answer.

In stark contrast, one man, John Harrison, dared to imagine a mechanical solution--a clock that would keep percise time at sea, something no clock had ever been able to do on land.

Longitude is a dramatic human story of an epic scientific quest and Harrison's forty-year obsession with building his perfect timekeeper, known today as the chronometer.

Full of heroism and chicanery, it is also a fascinating brief history of astronomy, navigation, and clockmaking, and opens a new window on our world.

 

From Kwit
 

Today I would like to recommend the nonfiction book, “Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time” by Dava Sobel.

Did you know that finding longitude was a problem for sea farers since the first time boats hit the water all the way to the eighteenth century?

Latitude is easy.

Look at the sun.

But apparently longitude was much, much trickier and incredibly easy to get wrong.

And if you got it wrong, people died.

It could be figured out if you knew what time it was where you were compared to what time it was at the port where you left.

But the thing was, the clock/watch you used to keep track of that had to be perfect.

No losing time.

No winding it up.

No worrying about oiling it.

Your watch losing even seconds of time meant you could be off hundreds of nautical miles.

In 1714 the British Parliament set a £20,000 reward for whoever could solve the problem.

To win the full prize, the method or device had to be accurate to within one-half degree on a trip from England to the West Indies.

Enter John Harrison, a self-educated village carpenter and clock maker. Lowly in status and not “fine enough” for society, this country bumpkin did what no one else could do before him.

Over several decades he was able to create the most intricate marine clocks and watches ever forged.

If he had created these as much as a century previously, he might have been accused of witchcraft. That’s not hyperbole.

His creations were so precise and ingenious that some of them still run today.

Also, the are absolutely GORGEOUS.

This first of his longitude devices was called the H-1, and looks like something HG Wells would have drooled over.

By the time H-4 came around, he created a longitude device that was slightly larger than a pocket watch.

Think of it this way: It would be like the SAME person created the first computers and then by the end of their life, created a smart phone.

From Charles Babbage to Steve Jobs in one lifetime.

I think the word “genius” gets thrown around too easily, but this Harrison absolutely astounded me with his genius.

Sobel’s account is short and very succinct.

There is no extra fat to it.

Facts and names and details.

But that by no means suggests that it wasn't a very good and informative read, with a clear protagonist and antagonist.

I urge you to come to the Sioux City Public Library and get your copy of Longitude and be astounded by the capabilities of human ingenuity.

 

Links :

• Monochrome : The Clock that Changed the World and the Fantastic Recreation of John Harrison’s H1
• BBC : Village at the heart of the race for longitude 
• GeoGarage blog : Navigating 18th-century science: Board of Longitude ... / Longitude - The story of a lone genius who solved the greatest ... / Hitting the books: How colonialism unified the Western ... / Lines of Longitude explained, with maps  / Map that misplaced Isles of Scilly and caused major ... / Why does the prime meridian pass through Greenwich?