The UK Centre for Seabed Mapping (UK CSM), a group of over 30 public sector organisations with a shared commitment to collect and share high-quality marine data, will undertake a seabed mapping survey – CSM2026 – to explore and map the seabed along the UK south-west coastline.

Throughout the four-week survey, using cutting‑edge survey technology deployed from the Research Vessel Cefas Endeavour, a team of 26 scientists from across the field of maritime research will collect vital hydrographic, geological and environmental data when they set sail from Lowestoft next week.

51ÁÔÆæ marine geoscientists Dayton Dove and Duncan Stevens will be on board, with a primary focus on acquiring sub-bottom profiler (SBP) data. An SBP is a type of sonar system, emitting sound waves that both reflect off, and penetrate through, the seabed to image the shallow subsurface. Those that penetrate through seabed reflect off the geological layers and buried structures, providing 2D cross-sectional images of the subsurface. This data (and resulting subsurface maps) are required for many offshore infrastructure applications, and importantly also provide further information on the nature, composition, and stability of the seabed itself.

Convening multiple government agencies, the survey represents an unprecedented level of collaboration within the maritime sector. By combining their skills and capabilities in a single survey, the team aim to secure data to deliver the UK government commitments and make advances in how our seabed is mapped, understood and managed.

51ÁÔÆæ are one of eleven UK CSM member organisations, which also includes: the Maritime and Coastguard Agency (MCA); the UK Hydrographic Office (UKHO); Centre for Environment, Fisheries and Aquaculture Science (Cefas); Department for Environment, Food & Rural Affairs (Defra), The Crown Estate; Historic England; Joint Nature Conservation Committee (JNCC); Agri-Food and Biosciences Institute, Northern Ireland (AFBI); Natural England and the Royal Navy.

Over the course of the survey, the scientists on board will have the opportunity to work with experts from other public sector organisations, share skills, and source key seabed mapping data that supports a wide range of applications including offshore energy and infrastructure, marine ecosystem science, safety at sea, marine policy, and defence. The four-week research survey is due to take place between 20 April and 19 May. This will consist of two survey legs, starting in Lowestoft, Suffolk and ending in Falmouth, Cornwall. All organisations are supporting the planning of alternative sites to maximise the opportunity.

“This is the first time that such a large-scale, multi-agency, collaborative survey has been undertaken in the UK and it a really exciting venture. We are fortunate to have expert scientists and surveyors from across government who will collect a wide range of highly valuable data. The partnership approach provides opportunities to share knowledge and expertise, as well as providing invaluable training and offshore fieldwork experience.

“The alliance of organisations is working together to increase efficiencies for data collection, processing and analysis under the gather once, use many times philosophy.

“Seabed mapping data provides the UK with a foundational basemap of its marine estate. Such valuable datasets are increasingly underpinning the maritime economy and energy security, enabling sustainable management of marine resources, development of marine policies and planning, and improves our understanding of the marine environment.�

Andrew Colenutt, Chair of the CSM2026 Project Team and Head of Hydrography and Meteorology at the MCA

“The UK CSM has proven to be an excellent forum for marine surveyors, scientists, and managers from across the UK public sector, increasing awareness, collaboration, and visibility of a disparate range of seabed mapping activities and applications.

This survey is an excellent opportunity for drawing the diverse expertise from across the UKCSM, and of particular significance for geoscientists, will include the collection of sub-bottom profiler (SBP) data. BGS has advocated for acquiring SBP data on hydrographic surveyors in order to provide crucial sub-surface data for a range of applications.

Scientists and decision-makers working in the offshore environment are reliant on high-quality seabed data to inform the siting, design, and installation of offshore infrastructure projects, such as Offshore Wind installations, habitat and ecosystem mapping, archaeology, marine aggregates, coastal erosion and management, and baseline geological and environmental science.”

Dayton Dove, BGS Marine Geoscientist

“This joint survey is a fantastic example of what public sector collaboration can achieve when expertise, capability and purpose are aligned. By bringing together organisations from across the UK maritime sector through the UK Centre for Seabed Mapping (UK CSM), we are not only improving how the seabed is mapped, but deepening our collective understanding of the ocean environment, while also providing an opportunity for various experts to learn from one another.

“High‑quality seabed mapping underpins everything from safety at sea and environmental protection to sustainable development and supporting national security. Working together through the UK CSM allows us to maximise the value of data, share knowledge, and deliver insights that no single organisation could achieve alone”

Rear Admiral Angus Essenhigh OBE, UK National Hydrographer & Director of Data Acquisition at the UKHO and chair of the UK CSM Steering Committee

About the UK Centre for Seabed Mapping (UK CSM)

The , administered by the UKHO, was established in 2022 and coordinates the collection, management and access of seabed mapping data. Through collaboration, the UK CSM aims to improve understanding of the UK maritime estate and inform the effective management of marine resources. There are currently over 30 public sector organisations who are members of the UK CSM with an interest in marine geospatial information and data.

Our digital geological maps are a unique national resource. A good understanding of the subsurface is critical for many applications across a wide range of disciplines, including, but not limited to:

• aquifer management
• radioactive waste disposal
• mineral resources
• engineering
• geohazards

Geological maps and digital data help with making investment and planning decisions, assessing hazards and de-risking projects. We are constantly aiming to update and improve our maps, so they are fit for the digital demands of the 21st century.

Why do we want your feedback? 

51ÁÔÆæ is constantly striving to improve its map compilation and dissemination procedures. The maintenance and development of our geological data is a vital part of our survey role. This is especially important as technologies change and offer new ways to disseminate information. The way we collect, compile and produce map data is also changing, so we are reviewing the way our maps and products are developed and delivered to our customers. 

Have your say 

Implementing effective change requires input from all our stakeholder groups and we’d like to hear from you. What are your current priorities? What problems are being solved using our data? What would you like to see in the future? BGS values your input and would appreciate you completing this short questionnaire, providing as much context as possible.

The Ascension Island Marine Protected Area (MPA) is one of the largest areas of protected ocean in the world and safeguards a unique ecosystem in the South Atlantic Ocean. It supports many species that are found nowhere else on earth, a mixture of deep sea and open ocean habitats that remain largely untouched and unexplored, whilst the island itself is home to thousands of nesting turtles and seabirds.

The 51ÁÔÆæ (BGS) recently completed a programme of high-resolution bathymetry surveys and drop-camera sampling within the nearshore areas of the Island. The survey team even managed to collect data where no other survey had ever been undertaken, which in addition to supporting conservation efforts, will also enable safer navigation in future.

The project was funded by the UK Government and utilised both BGS and Royal Navy bathymetry (depth), backscatter (seabed composition), ground-truth sampling (underwater video footage) and many other derived data layers to create the suite of bespoke geological outputs.  

The maps, which include seabed geology (substrate and geomorphology) and habitat, are the first to be created for the Island and determine the character, distribution and extent of the nearshore habitats of the MPA.

The geomorphological map revealed a collection of previously unmapped volcanic, erosion-depositional and coastal features including seamounts, submerged lava flows, ridges, submarine landslides and channels. Whilst the substrate map focused on the nearshore areas, composed of sandy sediments and rocky outcrops which are fundamental habitats for the marine communities. Both maps have enhanced the understanding of seabed processes and geological processes occurring around Ascension Island and enabled the creation of seabed habitat maps which provide unprecedented insight into the diverse ecosystems present in the surrounding waters.

As part of the project, the BGS Marine team provided training to the Ascension Island Government (AIG) in how to effectively use GIS software to view, edit, query and manipulate the data. The intention is for AIG to modify these maps as new data and knowledge becomes available and the management requirements of the protected area changes. Although the region is rich in biodiversity it is one of the habitats most at risk from anthropogenic development and climate change. The maps and data will be a vital resource for the AIG Conservation team as they continue to manage and safeguard the region.

“Collecting data in such a remote and exposed location was a challenge, but an absolute privilege and pleasure. BGS had to adapt existing technology to work with the available survey platform within the limits of Ascension wonderfully varied and unpredictable operating environment.�

Rhys Cooper, BGS Project Manager and Senior Surveyor

“The collection of new high-resolution datasets around Ascension Island allowed us to map the seafloor geology in unprecedented detail, uncovering critical geological features and habitats that support a rich diversity of marine life, and marks a significant milestone in our understanding of Ascension Island’s marine environment.”

Catriona Macdonald, BGS Marine Geoscientist

“AIG are excited to have access to such high-quality bathymetry and habitat maps. They will be transformative in our nearshore research and monitoring and allow for much more evidence based conservation management.”

Tiffany Simpson, Director of Conservation and Fisheries, Ascension Island Government

The final maps were delivered by BGS to the Ascension Island Government Department of Conservation in February 2025 and will be used by the team to manage the marine environment for future generations.

Further information

51ÁÔÆæ completes first mapping expedition to Ascension Island

In photos: Marine surveying a remote volcanic island

This project is funded by the UK Government through .

I’m Catriona Macdonald from the 51ÁÔÆæ Marine Survey team. My colleague Rhys Cooper and I recently returned from fieldwork on Ascension Island, a remote volcanic island in the South Atlantic Ocean. The reason for our visit was to complete a marine survey of the nearshore waters within the Ascension Island Marine Protected Area (MPA), one of the largest MPAs in the world.  The survey is part of the first stage of a project funded by the UK Government through to map the seabed and nearshore habitats within the MPA.

Working with the Ascension Island Government (AIG) marine conservation team, we acquired new, high-resolution bathymetry data in specific nearshore areas around the island as part of an integrated programme of marine surveys. The data will be used to produce the first geomorphology, substrate and habitat maps of the MPA. These will help to inform better management and monitoring of the marine environment, as well as enhancing our geological understanding of the sea floor around Ascension.

Completing a marine survey at the best of times can be extremely difficult, but, given the remoteness of Ascension Island, this project presented its own unique set of challenges. To get to Ascension, we had to travel down from Edinburgh to RAF Brize Norton, Oxfordshire, and fly overnight on the ‘South Atlantic airbridge’, which stops at Ascension for refuelling before continuing to the Falkland Islands. Thankfully, the flight now goes directly to Ascension: major repair work on the island runway led to the suspension of airbridge flights in 2017, meaning that the flights were diverted via Cape Verde. The runway opened again in 2022.

Chief surveyor Rhys considered several boat options before settling on a RIB-mounted system to complete the survey. The solution was ideal for surveying in shallow, nearshore waters, but it meant that the working conditions were challenging due to the size of the boat, the amount of survey equipment on board and the limited cover from the elements.

The food supply on Ascension is limited and depends on supplies that are flown to the island. However, we made good use of the fresh produce from the local hydroponics laboratory, which opened in 2016 and sells leafy crops, tomatoes and potatoes in the local shops. On our last weekend, our hosts from AIG took fishing rods out on the boat and at the end of the day we had a go at fishing. I was lucky enough to catch a yellowfin tuna, which meant we ate very well over the last few days!

Ascension amazing landscape and wildlife made the trip more than worthwhile. Over the course of our trip, we completed many of the hiking trails around the island. We even managed to source some (very old) golf clubs to have a go at the infamous One Boat Golf Club, which is sometimes playfully referred to  as the ‘world worst golf course’. The team will return to the island in January 2024 to collect seabed samples and participate in outreach activities for local government and community groups living on the island. 

This project is funded by the UK Government through .

On 30 October 2023, BGS project manager and senior surveyor Rhys Cooper and marine geoscientist Catriona Macdonald took the 4000-mile journey to Ascension Island, an isolated volcanic island in the Atlantic Ocean, to undertake the first stage of a UK Government-funded project.

In 2019, BGS was awarded funding from the UK Government through , a grant scheme by the Department for Environment, Food and Rural Affairs (Defra) that funds projects aiming to protect unique biodiversity and improve resilience to climate change within the UK Overseas Territories. Following a four-year delay due to COVID-19, the project is now underway. The first expedition focused on mapping the shallow waters surrounding Ascension Island, including an area of the island that has never been mapped or surveyed before.

Working with the Ascension Island Government, this BGS-led project will determine the character, distribution and extent of the nearshore habitats of the Ascension Island Marine Protected Area (AI-MPA) through an integrated programme of surveys. The AI-MPA is rich in biodiversity; however, protected areas such as this are most at risk from anthropogenic development and climate change.

Resulting sea-floor habitat maps will provide the Ascension Island Government with urgently needed tools to better monitor and protect marine ecosystems, as well as underpin the evidence-based management of the AI-MPA. The data will be merged with an existing dataset collected by the Royal Navy UK Hydrographic Office (UKHO) in 2021, which has already enabled the deployment of an array of sensors to monitor the movement of sharks. The combined datasets will also allow the first detailed geomorphology, substrate and habitat maps to be produced for the island, down to a maximum depth of 1000 m.

Ascension Island is a remote location and therefore presents many unique challenges that need to be overcome if we are to be successful. We have had numerous delays that proved fortuitous: the Royal Navy completed a survey around Ascension Island during COVID-19 lockdowns, which significantly reduced the amount of data we needed to collect, lowering costs and enabling us to refine and focus our survey campaigns.

The Ascension Island Government owns a boat that was made available to the project. This simplified logistics but required a totally different methodology for deploying the survey equipment. An appropriate solution was found and trialled in the UK before shipping the equipment to Ascension Island. This ‘warm-up’ survey allowed us to check it worked, was safe to operate and ensured we had all the equipment needed.

Rhys Cooper, project manager and senior surveyor.

The team is set to return to Ascension Island in January 2024 to complete the next stage of the project, which will focus on seabed sampling. A high-definition drop camera with laser scaling will be deployed to enable accurate mapping of the sea floor. The project is expected to be completed in April 2024.

This project is funded by the UK Government through .

Sail across the surface of an ocean and beneath you lie hundreds of millions of cubic miles of mystery — and what lies at the bottom is shadowier still. Underwater landscapes the size and complexity of continents, unknown ecosystems and processes that defy study from the surface means there are many gaps in our knowledge that science is hoping to fill. Due to the challenges of research at even moderate depths, almost every expedition venturing below 3000 m throws up a surprise.  

The Trans-Pacific Transit Expedition

The Open Ocean Research Program kicked off in early June 2023 on its first exploratory voyage entitled the ‘Trans-Pacific Transit Expedition’. Study will be based around a series of transits in the south-eastern Pacific Ocean that will continue through November and December 2023. The multidisciplinary team is composed of scientists from:

• 51ÁÔÆæ (leading geology)
• (biology)
• (physical oceanography)
• (ocean research)

Inkfish is also financing the project.

The researchers aim to engage local nations, for whom evolving oceanic processes have measurable impact day-to-day, and use the assets of all partners to make our view of the deep ocean sharper than ever before.  

The game changer with what we hope to achieve here is scale. No other programme can support multiple, global, repeatable series of complementary research expeditions. Of course, we will find new features and new species — but that is almost a bonus to the work we hope to undertake.

Heather Stewart, BGS Marine Geologist and primary investigator for the programme.

A rich field for research

This first expedition has three principal aims:

• conduct a detailed survey of the little-known fauna encountered to study their abundance, biodiversity and genetics
• fill in the many gaps in the geological maps of the world they inhabit to understand the structures, processes and habitats of the deep sea
• analyse the dynamic oceanic systems over a large latitudinal and longitudinal area 

The project will focus on the Pacific abyssal plains. The six legs of the expedition will use technologies such as free-fall landers, armed with a scientific payload to make in situ observations at full-ocean depth, and submarine survey equipment such as multibeam echosounders capable of mapping even extreme points of the sea floor from a surface vessel at superior accuracy.

Deep-sea exploration is always going to be tricky given the sheer water depths we are working in. We hope to reveal sea-floor features such as preserved spreading fabrics and knolls and seamounts that have recorded a history of volcanism, ridges and faults. We will cross multiple fracture zones that record offsets in the mid-ocean ridge where crust is created. The sea-floor video will give us insights into the composition of the seabed and the biological communities that live there.

Heather Stewart, BGS Marine Geologist

Several of the features surveyed over the course of the six-month Trans-Pacific Transit Expedition, which ends in Tonga in January 2024, will be ‘new’ — features that existing, low-resolution satellite altimetry data have thus far failed to resolve. 

Over 50Ìýper cent of the planet lies at a depth of nearly 4000Ìým and the Pacific Ocean hosts the greatest area of abyssal plains: 47Ìý555Ìý030 km². Locations around the Pacific Rim, such as Japan, Hawai’i, California, Chile and Aotearoa New Zealand, have collected significant baseline data in their waters. However, there is little to connect these datasets across these intermediate expanses of water.

Sampling efforts on the abyssal plains have been severely constrained by limited time and resources. As a result, large spatial and ecological patterns in species diversity, abundance, genetic links and habitat characteristics remain poorly understood across the wider Pacific basin.ÌýThe scale of data acquisition undertaken during this expedition is unprecedented.

, chief scientist of the expedition based at the .

Hades of the deep

The (named for Hades, the Greek god of the underworld) represents the most enigmatic of undersea terrains. At depths ranging from 6000 to 11 000 m, this zone includes the planet deepest and most remote ocean trenches. Found in seismic regions where tectonic plates meet and plunging deeper than Mount Everest is high, the trenches have long been out of sight and reach to all but the most specialised expeditions.

Despite only a quarter of a per cent of the world sea floor being in the hadal zone, it accounts for just under half (45 per cent) of its entire depth column. Most of these ocean-abyss environments are found in the Pacific, around the so-called Ring of Fire where the sea floor is being dragged beneath continental plates in subduction trenches that can reach enormous depths. Later expeditions in the Open Ocean Research Programme hope to visit a number of these in 2024.  

Heather, who is leading the expedition geological exploration of the seabed and its evolution over time, is no stranger to the challenges and potential of extreme depths: previously she was chief geologist for the . The vessel from this record-breaking challenge has been re-named to RV Dagon and the submersible re-named to Bakunawa, with both forming an integral part of this new research programme. The research craft present an opportunity that is fiercely rare: Bakunawa is one of only two operational craft in the world capable of reaching , the most extreme point of the planet surface lying just short of 11 km beneath the waves.  

Accidental discoveries on the ocean floor

The history of sea-floor exploration has thrown up its share of accidental discovery. Much insight into the oceanic landscape of the Pacific came courtesy of professor and navy commander Harry Hammond Hess during the Second World War. Results from his echo sounder running constantly yielded a landscape profile that formed the basis of his 1962 paper, ‘‘. His analysis of the plains, guyots, ridges and trenches birthed the concept of sea floor spreading, work that was further refined into the theory of plate tectonics by Canadian and British scientists. Their analysis of military magnetometer readings found symmetrical stripes of alternating polarity in sea-floor rocks either side of oceanic ridges, giving a timestamp for the Earth many magnetic inversions and the evolution of the sea floor.

More recently, the most accurate measurement for the Challenger Deep (10 983 m) was determined not by intention, but from calculations made from the sonic signature of an implosion of a scientific instrument.  

These all show just how hit-and-miss discoveries have been regarding the terrain that covers some 71 per cent of the planet surface and how purposeful targeted research with state-of-the-art equipment could be.

A new kind of expedition

With the multidisciplinary, repeatable nature of the Open Ocean Research Programme, scientists on board hope to use the unique platform to enhance the quality of data collection to a level impossible with traditional research expeditions.

For me, the opportunity to undertake multiple expeditions in one large geomorphological feature such as a subduction trench is unprecedented in our field. Working across disciplines with engineers, biologists and oceanographers is always something I enjoy as the extra dimension you get from working outside your own field frequently throws up new questions to explore and a new twist on how we view the data.

Government-funded research tends to support standalone projects rather than those undertaken as part of an ambitious, coherent network of global expeditions. Inkfish have provided us with a unique opportunity for open ocean exploration and discovery.ÌýThe flexibility to remain in one geographic area for more than one cruise allows us to acquire a comprehensive dataset with which we can test multiple, cross-discipline hypotheses.

All the research we will undertake will be published open access, so any interested party can explore our findings, whether for planning and decision-making purposes as part of the blue economy and conservation or to guide future offshore expeditions implemented by other groups around the world.

Heather Stewart.

Inkfish, meanwhile, is pleased to support marine researchers from around the world, bringing together diverse perspectives to collectively understand the deep sea. The team hopes to share discoveries as the expedition progresses.

About the author

51ÁÔÆæ released its first interactive isotope biosphere map in 2018, which enabled users to enter isotope data and find spatial matches and exclusions that helped source their samples. This is primarily used to help archaeologists study and identify human and animal migration, but it also has applications in the modern world of animal migration and food characterisation.

New sulphur isotope variation component

As part of an upgrade to the online map, we have now included a sulphur isotope variation for Great Britain. The beautiful map has been produced through sulphur isotope analyses of over 500 plants from across Britain. This has only been made possible by the reduction of modern sulphur pollution, which, until recently, swamped the natural sulphur signal.   

The plants’ sulphur isotope composition varies between values of around +20 parts per thousand in areas affected by modern marine influences, down to negative values as low as around -30 parts per thousand where the plants are growing in areas of anoxic reducing conditions.  

Sulphur values

The data has been formed into domains using a method called inverse distance weighting, with a superimposed marine domain for the coastal region. The resulting map highlights the following features that have not been seen before.

Firstly, there is a zonation of plant sulphur values from north to south, with the high marine influence that extends into central Scotland caused by prevailing wind conditions, transporting rain and sea spray inland.

In southern England, there is an area of negative values running from Peterborough to the Somerset Levels. These are areas underlain by Jurassic mudrocks. Recent research has shown that this lithology supports low and often very negative sulphur isotope values. These are due to both the reducing conditions during deposition and the rocks’ impervious nature, which leads to contemporary wetland development.

The coastal sulphur zone is based on traverses inland to assess the extent of sea spray influence. This work shows that there is a greater coastal zone on the west compared to the east coast.  

Further map upgrades

In addition to the sulphur map, the website upgrade includes an updated strontium (Sr) isotope map, which is now based on geological domains. Updates to this map identify new areas where elevated ⁸⁷Sr/⁸⁶Sr values are recorded. These include the granites of south-west England, especially around their thermal aureole, and Sherwood Forest, where the ancient woodland has leached out carbonate to leave ⁸⁷Sr/⁸⁶Sr-rich substrates.

As ⁸⁷Sr/⁸⁶Sr provenance studies are increasingly used on animals as well as humans, the land usage of these species need to be accounted for. Whereas human teeth mineralise over one to three years and are thus an average of all the strontium dietary inputs over this time, herbivore teeth can be sampled to represent only a few months of ingestion, which might well represent a single field.

Two levels of strontium data are now available in the search system. The first uses the central 50 per cent of plant data to equate to human consumption, whereas the second uses the central 90 per cent of the plant data to account for the greater variability in herbivore teeth.

A lead (Pb) isotope layer has also been added. This is based on mineral compositions and its aim is to produce a basic discrimination for England, Wales and Scotland based on the age of mineralisation in these areas.

Usage

Use of the map is free and all data is accessible and downloadable. We would be very interested to hear from potential users about any applications, development ideas or comments they have and hope to collaborate with users to continue to develop this resource through time.

Developers

The database and map have been created by:

• Jane Evans and Carolyn Chenery from the
• Katy Mee and Andy Marchant from BGS Informatics

About the author