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’s 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.

BGS 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’s commitments and make advances in how our seabed is mapped, understood and managed.

BGS 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’s 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’s 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.

The British Geological Survey (BGS) has released a new shallow subsurface geological synthesis of the southern North Sea in the first formal review of this region since the 1990s. A wealth of new subsurface data has been generated through the rapid expansion of offshore wind farm (OWF) development since the last assessment.

In total, the new synthesis draws on data from 22 OWFs and cable landfall sites from recent publications and open data available through The Crown Estate’s . Bringing these diverse datasets together presented a rare opportunity to enhance our geological understanding of the region, providing a detailed baseline resource to support more efficient and better-informed offshore development projects in the future.

Findings from the updated review have revealed much greater geological complexity within the region than indicated by the previous assessment, which was developed between the 1970s and 1990s on the back of data collected during oil and gas developments. Modern OWF investigations, supported by comprehensive borehole drilling, cone penetration tests and seismic datasets, show that many of the geological formations contain a variety of distinct sedimentary characteristics. This complexity has direct implications for foundation design and ground modelling, including the identification of geo-engineering constraints and geohazards, which is crucial information for a wide range of offshore infrastructure development.

The assessment examined evidence across pre-glacial, glacial, interglacial and post‑glacial periods from 200 million years ago to the present day. Understanding how different sedimentary units were deposited provides vital insight into geological formations that may present specific geo-engineering complications. This includes mixed soils, boulders, glacially compacted sediments or organic-rich layers. Organic units can be problematic for cable installation due to their fibrous nature, presenting considerable challenges to cable routing.

It is not a requirement for UK offshore infrastructure projects to collect samples for dating and biostratigraphy; however, where they are available, absolute dating (radiocarbon and optical stimulated luminescence data) information has also been included within the assessment. Neighbouring countries such as the Netherlands recognise the value of this data, as it can help to better predict age-based sedimentary characteristics and ultimately better inform geotechnical characterisation around a project’s design.

The report outlines several recommendations to enhance the resource further, including improving fine-scale mapping, ingesting geotechnical datasets for each geological subunit and strengthening international collaboration to harmonise North Sea stratigraphy. The findings presented in the main report can be aligned with results presented in the , which is a data catalogue highlighting the key geological features and associated engineering constraints for OWF development as part of the . Both resources provide complementary datasets and criteria essential for evaluating OWF site suitability.

This work provides:

• an opportunity to advance scientific understanding
• resources to strengthen national collaboration
• supporting baseline evidence for the energy transition, energy security and wider marine planning
  

The release of this report marks an important milestone in compiling geological observations from literature and offshore wind farm development over the past 30 years or so. It brings together a wealth of new offshore geological data that enhances our understanding of the shallow subsurface in the marine environment in the southern North Sea. We hope this dataset will provide strong baseline evidence to support national and international collaboration for efficient offshore development and act as a blueprint for other areas around the UK Continental Shelf.

Nikki Dakin, BGS Senior Marine Geoscientist

We would encourage similar consolidation of geological information across the wider North Sea, Celtic Sea, Irish Sea, The Solent and English Channel, making full use of the substantial dataset holdings within the Marine Data Exchange. There is also significant potential to extend this approach internationally, working with neighbouring countries.

Such data provides a robust evidence base for industry, regulators and researchers, marking an important step toward a fully modernised geological model and improving our understanding of offshore stratigraphy across the UK Continental Shelf.

The report and geological assessment are now available online: .

BGS would like to acknowledge The Crown Estate as well as wind farm developers for contributing reports and data to The Crown Estate’s Marine Data Exchange.

BGS has developed a new, national-scale, offshore dataset that shows the distribution of previously interpreted Quaternary rock layers in the shallow subsurface of the UK continental shelf.

The BGS Offshore Quaternary 250K dataset��comprises a compilation of legacy BGS 1:250��000 Quaternary geology map sheets, which were first published in the late 1980s to early 1990s. Large areas of the UK offshore are covered at a scale of 1:250��000 and this is the first time these map sheets have been digitised and merged together.

The dataset is made up of vector polygons, each representing an area where a particular formation has been mapped. The legacy map sheet interpretations have not been modified during the digitisation; they are presented in their original form and have been ‘mosaiced’ together as a single digital product.

The dataset will help users, particularly those in the offshore renewables sector, to understand the stratigraphy that was mapped historically in a particular area and can be used for reference when completing site investigations.

The principal drive behind this release is to make original 1:250��000 map data available in a digital format. Although work to refine Quaternary stratigraphical frameworks is ongoing, the map compilation is not informed by new data or analyses.

The Offshore Quaternary 250K dataset is the first time that these legacy offshore map sheets will be digitised, making it easier for users to access the data than ever before.

Andrew Dyson, marine geoscientist at BGS.

Renewable energy infrastructure, whether on- or offshore, requires in-depth understanding and accurate characterisation of the underlying geology.  Developers increasingly need detailed geospatial observations of the seabed and shallow subsurface, which are critical to the siting and design of offshore infrastructure such as submarine cables and offshore wind turbines. This is certainly true in the Bristol Channel, which is home to the second largest tidal range in the world. This high-energy environment has attracted much interest around the use of the seabed for tidal power and the potential to produce electricity from wave energy.

To support policy- and decision makers in this region, BGS has released an enhanced seabed geology map of the Bristol Channel, almost four times the size of the original, which extends from Carmarthen Bay to Newport and further south to the coast of Somerset.

Beyond offshore infrastructure, these maps also directly contribute to understanding of marine ecosystems, coastal management and defence activities. The data provides crucial information to those ensuring the port facilities along this coastline meet the requirements for these development opportunities.

As the UK’s transition to renewable energy gathers pace, these maps will become increasingly valuable to industry and stakeholders with an interest in developing clean energy, from offshore wind to tidal streaming, and in carbon capture and storage.

The successful implementation of offshore renewable energy projects and technologies and the development of ports in South Wales require a detailed understanding of the seabed. This new, expanded, fine-scale seabed map of the Bristol Channel will be an invaluable resource for developers, providing access to high-quality, detailed observations of the seabed geology that is vital to these kinds of developments.

Beyond its critical role in supporting the renewables sector, the map will also be useful to other data users, such as those involved with supporting marine ecosystems, coastal management and defence activities. It will also provide evidence for policy- and decision makers in the region.

Rhian Kendall, BGS Chief Geologist for Wales.

The map, featuring combined bedrock, sediment, bedrock structure and seabed geomorphology data, is available from BGS under the fine-scale maps section of the����and is designed to be viewed at 1:10��000 scale, or online as downloadable shapefiles. For information on licensing the downloadable GIS data (ESRI format), please contact digitaldata@bgs.ac.uk.