Beneath the seas: the adventure of marine cartography

 

 The Brest harbor and its surroundings in 1820, with numerous measurements taken one by one to determine the depth at each point. | SHOM

 

From Ouest France by Angellina Thieblemont

“Some Maps Remain ‘Classified’”: 

The History of Nautical Charts Told at the Brest Naval Museum

The exhibition at the Brest Naval Museum, “Beneath the Seas: The Adventure of Marine Cartography,” opens on June 26.

It traces the evolution of this practice over the past 500 years, as well as its military, archaeological, and economic uses—aspects largely unknown to the general public.

Stories of shipwrecks lost in Brest Harbor (Finistère), British blockades of the port, and maps classified as “defense secrets”… 

All these stories have one thing in common: they chronicle the development of underwater cartography in the new major exhibition at the Brest Naval Museum (Finistère), which opens on June 26, 2026.

 

Brest, home to the world’s oldest underwater mapping service

To mark the 400th anniversary of the French Navy, an exhibition on “The Call of the Deep” is being held in Paris, Toulon, Port-Louis, Rochefort, and Brest.

Each location of the National Maritime Museum explores a different aspect of this exploration of the ocean depths.

In Brest, the focus is on the history of marine cartography, from the 16th century to the present day. 

It is no coincidence that this theme was assigned to the “City of the Ponant”: since 1971, Brest’s Bergot district has been home to the Navy’s Hydrographic and Oceanographic Service (SHOM).

Founded in 1720, it is the oldest marine mapping service in the world.

 

A rare document depicting the Crozon Peninsula, Pointe Saint-Mathieu, and the Brest harbor, known as “Baye de Breft.” | NATIONAL MARITIME MUSEUM

In two rooms, shielded from the heat wave by the fort’s thick walls, the exhibition explains why and how nautical charts have been made since the 16th century. Among the hundred or so works on display are period maps featuring drawings of the monsters believed to lurk beneath the sea’s surface, as well as parchments, paintings, models, and a full-scale replica of a chart room complete with period tools…

Visitors also learn about the story of Charles-François Beautemps-Beaupré, the father of modern hydrography. In the 19th century, this pioneer set out to survey the coast of Brest. It was one of the first seabeds in the world to be mapped. On one of his maps, thousands of numbers are scattered across a drawing of the harbor. They give a sense of the titanic undertaking: for each point, a rope with a lead weight was lowered from their small boat and used as a sounding line.

 

A map of the Mediterranean and the eastern Atlantic, 1537. This map was painted on parchment by Vesconte de Maggiolo (1457–1530). | NATIONAL MARITIME MUSEUM

Deliberately Falsifying Maps

The exhibition features several thematic sections, highlighting the many fields in which hydrography is useful, particularly in archaeology and the installation of internet cables.

Brest. Me, the mayor...

But since the 16th century, this science has been most widely used in the field of defense: mapping sandbars to avoid running aground during battles, creating false maps that omit hazards to trap opponents… 

Such was the case with the Rocher de la Rose, an obstacle that loomed at the entrance to the Penfeld channel until the 19th century and was blown up by divers. 

It was deliberately omitted from maps in order to cause enemy ships to run aground. 

Visitors can also view one of the maps of the Normandy beaches that was used to prepare for the 1944 D-Day landings.

 

 

The 1842 painting *Combat du Grand Port* depicts a battle in which a British ship is defeated and runs aground on sandbars, while the French ships—which benefit from highly accurate nautical charts—escape unscathed. | NATIONAL MARITIME MUSEUM/A. FUX

 

Only 26% of the ocean floor will be mapped by 2026

Today, some maps are classified as defense secrets because of their quality and accuracy. 

“Accuracy is a weapon,” explains Jean-Yves Besselièvre, director of the National Maritime Museum. Since the 16th century, only 26% of the planet’s ocean floor has been mapped. 

“We’ve mapped the surface of the moon better than we’ve mapped the ocean depths,” says Jean-Yves Besselièvre.
Titled “Beneath the Seas: The Adventure of Underwater Cartography,” the exhibition runs through March 2027. 

A family guidebook has been created for children.

It allows them to explore the exhibition in a fun way by inviting them to conduct a mini-investigation.

The wildest shoot of my career (Benjamin Hardman)

Here are a couple of unseen angles from the moment I witnessed a Polar Bear attempting to hunt a Beluga whale pod in the Arctic pack ice, located in the marginal ice zone between Svalbard and Greenland.

This whole moment unfolded so quickly and revealed the sheer intensity that can arise out of nowhere in these otherwise very calm and desolate sea ice landscapes.

Collapse of AMOC ocean current may already be locked in

A visualisation of Atlantic Ocean currents based on sea surface temperature dataNASA/Goddard Space Flight Center Scientific Visualization Studio

From New Scientist by Chris Simms

 

The fate of the Atlantic Ocean current that keeps Europe’s climate warm depends on our carbon emissions and the rate of ice melt from Greenland, but there is a chance that a shutdown is already inevitable

 

 A potentially catastrophic collapse of the Atlantic Ocean currents that control Europe’s climate may already be inevitable.
Based on model simulations, researchers estimate that there is a 10 to 23 per cent chance that such a collapse is locked in.

“There is a significant probability that we’re already committed to collapse, and we can’t change that even now,” says Phil Holden at the Open University, UK.

The Atlantic Meridional Overturning Circulation (AMOC) carries warm, salty water from the tropics into the North Atlantic Ocean, where it cools, sinks and then returns south.
This circulation regulates the climate across Europe, Africa and the Americas.

Recently, there have been signs that this vital current system is weakening, including by slowing in some areas, partly because the melting of the Greenland ice sheet caused by climate change is making the salty water less dense, so that it sinks more slowly.

Some scientists have suggested that the AMOC could collapse, plunging Europe into near-Arctic conditions and weakening monsoon systems around the world.
One recent study found the AMOC could cross a tipping point within decades, but it is difficult to say how likely this is.

“The AMOC collapse has just been so intangible,” says Holden.
“So far there’s been no firm quantification of whether it is going to happen or when it is going to happen.”

“There’s a lot of uncertainty, and a lot of different opinions among the expert scientific community,” says Tim Lenton at the University of Exeter, UK.

To get a better idea of what might happen to AMOC, Holden, Lenton and their colleagues ran 21 computer simulations with varying rates of Greenland ice melt and emissions peaking at different dates, at 10-year intervals from 2005 through to 2135.
The team assumed that, after the peak, greenhouse gas emissions would fall to net zero over 35 years while the melt rate of Greenland ice would stay constant.
Each simulation ran for a total of 300 years.

The models indicate that under very conservative assumptions – emissions peaking in 2025 and the Greenland ice sheet adding just 54 millimetres to sea-level rise by 2100 – there is a 10 per cent chance that the collapse of the AMOC is already inevitable.
The researchers defined this as when the circulation would only occur at lower latitudes, and when the overturning current that brings heat to the high latitudes has stopped.

If we don’t start on the path to net zero until 2100, the probability of collapse rises to 80 per cent, the model predicts.

Under less conservative assumptions, with melting ice from Greenland adding 274 mm to sea-level rise, as is projected by 2100, the probability that we are already committed to collapse is 23 per cent.

Even when a collapse becomes inevitable, it would take a long time to happen.
In the simulations, the average delay between the year in which the world becomes committed to collapse and the collapse coming to pass was 84 years, with the earliest collapse occurring around 2060.

“This idea of talking about committed collapse, rather than when the collapse actually happens, frames it in a way that’s quite interesting for risk management,” says Till Wagnerat the University of Wisconsin-Madison, but he is cautious about extrapolating to the real world.
“I think there’s fairly good evidence that there’s going to be a weakening, but the actual larger-scale dynamical outcome is still very much up in the air.”

Jonathan Baker at the Met Office, the UK’s national weather service, says the simulations provide a valuable way to explore how the AMOC responds to different scenarios, but the low resolution of the model used means it isn’t as sensitive as some other climate models, which might influence its estimates of risk.

Many state-of-the-art climate simulations can compute the globe in grids of 1° of latitude and longitude, which takes huge amounts of computational resources and time to run long-term simulations.
The model used in this study uses 5° grids, but this low resolution was a deliberate choice, says Lenton.

“There isn’t the compute power, or no one’s had the ability to do this exercise with a higher-resolution model,” he says.
This does mean the probabilities of the risk estimates could be different at higher resolution, he says, but recent research on the AMOC using a higher-resolution model indicates that, if anything, this might raise rather than lower the estimates.

“Further work using multiple climate models and comparison with the wider body of evidence will be important before drawing reliable conclusions about the magnitude of future AMOC collapse risk,” says Baker.

If there is a chance the world is already committed to AMOC collapse, as the model suggests, this should provide extra incentive to cut emissions, says Lenton.
This is because the model indicates that the probability of AMOC collapse rises sharply if net zero is delayed.
If emissions continue unabated for 10 extra years beyond the point of commitment, the actual collapse would happen faster – after 57 years, on average, rather than 84.

“What the model is saying to me is ‘let’s do everything in our power to get to net zero as quickly as possible to try to keep this probability down at the 10 per cent level’,” says Lenton.

This chimes with research published last month hinting that the slowdown of the AMOC may be reversible – if carbon dioxide emissions come down enough.

Links :

• EarthArXiv, DOI: 10.31223/X5N48Q
• Arctic Today : AMOC collapse may already be locked in, new study suggests 

Occupational risk ? Chinese presence surges at Scarborough Shoal

From AMTI CSIS

Midway through 2026, Scarborough Shoal remains the focal point of Philippine-China frictions in the South China Sea, with recent tensions stemming from China’s deployment of floating objects at the shoal, including buoys, floating barriers, and most recently, a temporary research structure.
But new data on ship movements reveals yet another cause for concern at Scarborough: a massive increase in presence from the China Coast Guard (CCG), the backbone of Beijing’s efforts to exercise control over the shoal.

 

A Chinese Coast Guard (CCG) patrol ship maneuvers next to a Filipino fisherman paddling a Philippine flag aboard a motorized wooden boat as they sail towards Scarborough Shoal in the disputed South China Sea, 16 May 2024. 

A civilian-led mission joined by at least a hundred fishermen embarked on Scarborough Shoal in the disputed South China Sea to assert the Philippines’ territorial claim. 

Scarborough Shoal (‘Bajo de Masinloc’ called by Filipino fishermen), a fishing haven shoal within the Philippine maritime territory that China occupied a decade ago, was recently reported to be driving away Filipino fishermen by Chinese coastguard ships. 

EPA/FRANCIS R. MALASIG

 A Look at the Data

To better assess recent activity at Scarborough Shoal, AMTI analyzed automatic identification system (AIS) data around the shoal from January 1 to June 30, 2026.
The data collected focused on documenting the presence of China Coast Guard (CCG), Philippine Coast Guard (PCG), and Bureau of Fisheries and Aquatic Resources (BFAR) vessels, as well as instances of interactions between these Chinese and Philippine ships.

The data shows that CCG patrols at Scarborough have significantly increased in 2026, a remarkable feat given that 2025 was already a record year for CCG presence at the shoal.
Through the first six months of 2026, CCG patrols at Scarborough amounted to 933 ship-days, nearly as much as 2025’s entire annual total of 1,099 ship-days (which itself had already doubled from 2024’s total of 516 ship-days).

On a monthly basis, CCG patrol volume increased from an average of 90 ship-days per month in the first half of 2025, to 156 per month in 2026, with ship-days peaking at 216 in May.

Scaborough shoal with the GeoGarage platform (UKHO nautical raster chart)

As has been the case since last year, some CCG operating near Scarborough conducted patrols along, and sometimes over, China’s claimed nine-dash line, positioning themselves to intercept Philippine ships heading toward the shoal.
But in comparison to previous periods, the density of patrol coverage near the shoal has markedly increased.
Multiple CCG ships were often seen coordinating to maintain a perimeter patrol, covering all approaches to Scarborough in an approximately 30 nautical mile radius.
And inside that perimeter, a persistent detachment of 6-8 Chinese maritime militia maintained similar coverage of the area closer to the shoal.

Philippine law enforcement patrols near Scarborough also increased in 2026, though they remained far fewer than those of the CCG.
PCG and BFAR vessels averaged 43 ship-days per month in the first half of 2026 compared to 30 ship-days in the same period last year, an increase of 43 percent.

Encounter between CCG 21563 and the BRP Datu Pagbuaya, and four other vessels on May 27, 2026

The frequent patrols have continued to lead to dangerous encounters between Philippine and Chinese ships.
Data for the first half of 2026 showed 112 days on which an interaction was observed between CCG and PCG/BFAR ships near Scarborough, averaging out to 19 days per month.
And in several instances, including a May 27 encounter between the CCG 21563 and the BRP Datu Pagbuaya, satellite imagery revealed the presence of additional ships not visible on AIS.

Floating Structures and Research Activities

Beijing’s redoubling of its coast guard patrols has occurred alongside other more creative Chinese initiatives at Scarborough.

Since China’s declaration of a nature reserve at Scarborough Shoal last September, Beijing has installed multiple floating structures in and around the shoal.
In the latest incident, the Philippines filed a diplomatic protest against China over a 6-by-6-meter floating structure that was found inside the lagoon of the shoal on May 25.
This was the first structure of its kind to be seen in the area, which raised alarms in Manila that Beijing was possibly beginning a larger buildout at the shoal.
Chinese official sources, including the Chinese embassy in Manila, eventually stated that the platform was a “temporary research facility” collecting data on the ecosystem of the shoal.
The deployment of the platform coincided with the end of a research expedition by a Chinese survey vessel, the Xiang Yang Hong 33, which spent several days at Scarborough in late May after conducting operations at multiple reefs in the Spratly Islands in the preceding weeks.

That platform was eventually removed on June 17, but other floating objects recently installed by China remain at the shoal. 

This includes two buoys installed last October, and several new objects identified by the PCG in May.

Pushing New Boundaries

China’s activities at Scarborough have entered uncharted territory.
The level of concerted CCG presence at the shoal in 2026 is beyond any previously observed CCG activity in the South China Sea since AMTI began regular AIS tracking in 2019.
And as Beijing doubles down on these familiar tactics, it is also employing new methods to enhance its physical presence and establish new patterns of (nominally) civilian activity at the shoal—all without crossing the traditional red lines of building a permanent structure or conducting land reclamation.
As Beijing pushes the boundaries of just how much control it can assert over the shoal, Manila and Washington would do well to keep a close eye on Scarborough.

 

Links :

• The Manila Times : CCG shoal presence highest this year
• Daily Tribune : CCG presence at Scarborough Shoal nearly matches 2025 total in first half of 2026
• MSN : CCG shoal presence highest this year 
  
  

Two centuries on, experts unlock secrets of Red Sea and Gulf of Aden sailing chart

The Indian, Kachchhi/Gujarati, document has been part of the Royal Geographical Society’s collection for 189 years

From Exeter 

 

 Experts have unlocked secrets hidden for two hundred years in a beautiful navigational chart made for 18th century seafarers negotiating the Red Sea and Gulf of Aden.

The paper scroll is evidence seafaring communities in the region used their own effective system of navigation that enabled trade and exchange between India, Arabia and the Horn of Africa in the age of sail, before the uptake of a more abstract, instrument-based navigation.  

The Indian, Kachchhi/Gujarati, document has been part of the Royal Geographical Society’s collection for 189 years and is one of the most detailed surviving indigenous navigational charts produced in the Indian Ocean tradition.  

New research shows it was an effective aide memoire, capturing and reflecting the intimate knowledge of sailors from modern Gujarat in India. It is a window onto the indigenous navigational practices of people across the western Indian Ocean.

Researchers have been able to identify and interpret place-names and astronomical data inscribed on the chart for the first time, establishing latitude and providing sailing directions and showing intimate local knowledge: the chart was not simply designed to facilitate long-distance transit to first-order Red Sea ports.

The chart, which is adorned with beautiful images of ships and religious buildings, dates from the late 18th or early 19th centuries.
It was acquired by Alexander Burnesin 1835 from an un-named sea captain in Kachch.
He donated it to the Royal Geographical Society.
However, he and subsequent scholars were not able to translate and analyze the map to extent that the current study has.

The 66 or so Devanagari place names on the chart have never been fully transcribed and identified and most European scholars who appraised the chart wrongly claimed that it had no latitude or longitude information.
They also thought the fact it did not show the ‘real’ angle of the Red Sea and Gulf of Aden as a shortcoming when in fact it makes the chart more portable.

Experts have produced a projection of the chart that presents the information it contains spatially in a way familiar from modern maps.

The cartographer who made the document depicts more than 180 islands, plus reefs and other features such as landmarks, religious buildings and flags.

Alexander Burnes, who lived from 1805 to 1841, acquired the chart while lieutenant in the East India Company Service and assistant to the British Resident in Kachchh.
Burnes had already won celebrity through his 1832 imperial expedition across Central Asia, which had resulted in a best-selling book,honours from London learned societies including the RGS and an audience with King William IV.

He declared it would “form a specimen of naval surveying … unequalled in any of the cabinets of Europe” and believed it had been a working document used on board ship.
But he didn’t realise it was a practical navigational chart.

The chart has been interpreted previously in 1947, 1987, 2002,2012 and 2022, but scholars have overlooked the chart’s navigational affordances.
Around half of the chart’s Devanagari toponyms were left unidentified and without locations—with more still lacking precision.

Researchers believe they have now found coordinates for all 66 toponyms and improved transcriptions of the Devanagari script. 

 

They have found that chart’s 29 rhumb lines serve three main purposes: establishing the principal trend of a coastline; indicating a direction of travel across open water; and, in possibly two cases, showing safe passage into and out of port.

Professor John Cooper, from the University of Exeter’s Institute of Arab and Islamic Studies, who led the research, said: “Today we are used to maps and charts that project space mathematically and to scale, making regions of the world visually familiar and accessible to us in a very particular way.
Although this chart doesn’t look accurate to our way of thinking, it allowed seafarers with the necessary experience and knowledge of stellar navigation to negotiate some of the harshest and most challenging waters in the world.
All the required information was packed into a very portable scroll just 25cm wide.

“This is a rich and effective navigational reference work: its stellar information allowed sailors to know their latitude and set sailing directions; its many place names and topographical information enabled them to locate themselves precisely; its religious buildings suggest the navigator’s Muslim faith; and its flags suggesting nodes of political and fiscal action.

“It was designed for those with specific local navigational knowledge.
Although rich, the inscribed information would not be enough to enable people uninitiated in regional seafaring traditions to navigate safely. But, for those who knew, it functioned as a handy reference at sea, fulfilling a mnemonic role. Its scroll format allowed it to be opened partially, showing only the relevant section, with the rest rolled away. It stored and handled easily on-board ship.”  

Dr Katherine Parker, the Royal Geographical Society’s Cartographic Collections Manager, said: “Re-examining our Collections is an ongoing process that allows researchers to apply new methods, technologies and perspectives, uncovering the meanings and utility that these remarkable artefacts held for the people who created them centuries ago.
We have been delighted to work alongside the team to bring a greater understanding of the navigational, geographical and cultural value of this chart, as well as the cartographic skill and knowledge of its creators, into focus.”

 

Links :

• LaBrujaLaverde : Secrets Uncovered in an 18th-Century Nautical Map Guiding Sailors Between India and the Horn of Africa
• Phys : Two centuries on, experts unlock secrets of Red Sea and Gulf of Aden sailing chart