This dataset contains level 2 vector formatted data derived from the Centre of Ecology and Hydrology's (CEH) Land Cover Map 2000 (LCM2000) data for the Thorney Island, South Coast of England, UK, NCAVEO calibration/validation (cal/val) test site. The NERC funded Network for Calibration and Validation of EO (NCAVEO) campaign was designed to illustrate and explain the processes involved in cal/val of earth observation data.

This dataset contains 25m resolution raster formatted data derived from the Centre of Ecology and Hydrology's (CEH) Land Cover Map 2000 (LCM2000) data for the Thorney Island, South Coast of England, UK, NCAVEO calibration/validation (cal/val) test site. The NERC funded Network for Calibration and Validation of EO (NCAVEO) campaign was designed to illustrate and explain the processes involved in cal/val of earth observation data.

The results of the habitat mapping exercise were derived from aerial photography interpretation (API). The shapefiles produced are available to holders of OS MasterMap licenses. The habitat mapping dataset is held at Plymouth Coastal Observatory however, the Environment Agency is responsible for the GIS data as it was creating using their MasterMap licence. The survey extends from Portland Bill in Dorset to Avonmouth in Bristol and includes the Isles of Scilly. The landward limit of the survey varied but in general is determined by one of the following: Extent of aerial photography; Indicative tidal floodplain; Sites of Special Scientific Interest (SSSIs); Extent of coastal BAP habitats; 5m contour with a 200m landward buffer ; Inclusion of other target habitats. The habitat map was originally created using the Integrated Habitat Survey (IHS) classification originally developed by Somerset Environmental Records Centre. The classification was broadened to include all coastal habitats in South West England. The IHS classification had been substantially modified for the purposes of the habitat mapping. THIS was converted to EUNIS L3 by Ian Saunders at NE and forms the data NE provided to the JNCC as part of the MCZ project ÔÇô Tranche 1. A MESH Confidence Score of 86 was assigned to the dataset based on the information given in the reports supporting the GIS.

Orthorectified aerial photography used was flown to a scale of 1:5000. Photography was flown at low tide on a spring tide between the months of April and September to ensure maximum vegetation coverage. As a result of this and due to adverse weather conditions over some of the key tidal windows the whole project area was not captured in one block, but flown in stages between 2006 and 2009. Although ground-truthing was undertaken to support and validate the habitat map, not all areas were ground-truthed.

The HABMAP project was set up in response to the need for better spatial awareness of habitat distributions in the Southern Irish Sea. This work produced habitat maps of the seabed using novel predictive modelling techniques. This dataset is related to the predictive modelling only. The HABMAP Extension Project has built on the methods developed during the original project, and has repeated the modelling work using higher resolution / improved input datasets to help increase the accuracy of the predictive map outputs. The modelling work has also been extended to cover all of Welsh waters (previously cut-off at the Interreg funding boundary), notably including the Dee and Severn estuaries. The purpose of this data capture was to provide seabed habitat maps that could be used for con servation and management. Project outputs might be used in strategic planning, decision making for offshore developments, Marine Protected Area selection, sensitivity mapping and mapping essential fish habitats. However, because of the way the has been produced, and the fact that some data has been modelled and derived, the maps are not appropriate to act as the sole evidence for any specific planning or regulatory decision or assessment without further supporting studies or evidence.

The project boundaries were as follows: Southern Irish Sea- land-based boundaries include the whole Welsh coast to the English border on the east side of the Dee Estuary in the north, and the whole Severn Estuary and Bristol Channel coastline in the south, extending as far as Morte Point (east of Ifracombe) in England. The southern project boundary then extends offshore (skirting the northern tip of Lundy) across to a point approx 60km west of Waterford on the Irish coast, including the whole SE Ireland coastline and offshore banks as well as parts of the Celtic Sea. The boundary then extends northwards along the Irish coast to a point approximately 40 km north of Dublin.

A Natural England commissoined verification survey of intertidal sediments within the Thanet Coast rMCZ. Phase I Biotope mapping was carried out across the rMCZ for broad scale habitats. The data was used to produce a EUNIS Level 3 boradscale habitat map of the Thanet Coast rMCZ.

This dataset consists of an interactive map (and supporting guidance) containing background information that informs how we understand flood risk across the South West River Basin District. The map shows the River Basin District, component river basins and the coastline together with layers showing land use and topography.

This dataset together with equivalent datasets for each River Basin District, supports the Preliminary Flood Risk Assessment for England report which has been written to meet the requirements of the Flood Risk Regulations (2009) - to complete an assessment of flood risk and produce supporting maps of river catchments.

The HABMAP project was set up in response to the need for better spatial awareness of habitat distributions in the Southern Irish Sea. This work produced habitat maps of the seabed using novel predictive modelling techniques. This dataset is related to the predictive modelling only. The HABMAP Extension Project has built on the methods developed during the original project, and has repeated the modelling work using higher resolution / improved input datasets to help increase the accuracy of the predictive map outputs. The modelling work has also been extended to cover all of Welsh waters (previously cut-off at the Interreg funding boundary), notably including the Dee and Severn estuaries. The purpose of this data capture was to provide seabed habitat maps that could be used for conservation and management. Project outputs might be used in strategic planning, decision making for offshore developments, Marine Protected Area selection, sensitivity mapping and mapping essential fish habitats. However, because of the way the has been produced, and the fact that some data has been modelled and derived, the maps are not appropriate to act as the sole evidence for any specific planning or regulatory decision or assessment without further supporting studies or evidence. The project boundaries were as follows: Southern Irish Sea- land-based boundaries include the whole Welsh coast to the English border on the east side of the Dee Estuary in the north, and the whole Severn Estuary and Bristol Channel coastline in the south, extending as far as Morte Point (east of Ifracombe) in England. The southern project boundary then extends offshore (skirting the northern tip of Lundy) across to a point approx 60km west of Waterford on the Irish coast, including the whole SE Ireland coastline and offshore banks as well as parts of the Celtic Sea. The boundary then extends northwards along the Irish coast to a point approximately 40 km north of Dublin. The outputs of the project included a Combined Level3/Level4 habitat map, presented here after translation to the EUNIS habitat classification system from the Marine Habitat Classification System for Britain and Ireland. Each polygon of the original output contained up to 46 different biotopes, either predicted by the model or recorded as present, and presented in order of likelihood. Only the primary biotope has been taken from the original dataset to produce this EUNIS output, polygons originally containing more than one habitat are flagged in the "VAL_COMM" field. Information on whether the biotope was recorded as present or was a predictive output of the model, and a confidence value present in the original dataset have also been recorded in the "VAL_COMM" field

This geophysical survey was carried out under contract for the Marine Aggregate Levy Sustainability Fund (MALSF) as part of a Regional Environmental Characterisation, the survey took place from the 8th March to the 18th March 2010. This project is to extend the mapped coverage of the Eastern English Channel Marine Habitat Map (EECMHM) to include the coastal platform from Saltdean east to Dungeness and provide an integrated map dataset covering this extension area The geophysical data was acquired using Surface Tow Boomer and Sidescan sonar equipment. Technical detail of the survey are contained in BGS Open Report OR/10/052.

Coastline for Antarctica created from various mapping and remote sensing sources, consisting of the following coast types: ice coastline, rock coastline, grounding line, ice shelf and front, ice rumple, and rock against ice shelf. Covering all land and ice shelves south of 60°S. Suitable for topographic mapping and analysis. High resolution versions of ADD data are suitable for scales larger than 1:1,000,000. The largest suitable scale is changeable and dependent on the region.

Major changes in v7.5 include updates to ice shelf fronts in the following regions: Seal Nunataks and Scar Inlet region, the Ronne-Filchner Ice Shelf, between the Brunt Ice Shelf and Riiser-Larsen Peninsula, the Shackleton and Conger ice shelves, and Crosson, Thwaites and Pine Island. Small areas of grounding line and ice coastlines were also updated in some of these regions as needed.

Data compiled, managed and distributed by the Mapping and Geographic Information Centre and the UK Polar Data Centre, British Antarctic Survey on behalf of the Scientific Committee on Antarctic Research.

Further information and useful links

Map projection: WGS84 Antarctic Polar Stereographic, EPSG 3031. Note: by default, opening this layer in the Map Viewer will display the data in Web Mercator. To display this layer in its native projection use an Antarctic basemap.

The currency of this dataset is May 2022 and will be reviewed every 6 months. This feature layer will always reflect the most recent version.

For more information on, and access to other Antarctic Digital Database (ADD) datasets, refer to the SCAR ADD data catalogue.

A related medium resolution dataset is also published via Living Atlas, as well medium and high resolution polygon datasets.

For background information on the ADD project, please see the British Antarctic Survey ADD project page.

Lineage

Dataset compiled from a variety of Antarctic map and satellite image sources. The dataset was created using ArcGIS and QGIS GIS software programmes and has been checked for basic topography and geometry checks, but does not contain strict topology. Quality varies across the dataset and certain areas where high resolution source data were available are suitable for large scale maps whereas other areas are only suitable for smaller scales. Each line has attributes detailing the source which can give the user further indications of its suitability for specific uses. Attributes also give information including 'surface' (e.g. grounding line, ice coastline, ice shelf front) and revision date. Compiled from sources ranging in time from 1990s-2022 - individual lines contain exact source dates.

Survey of the inter-tidal areas between Burnham Overy and Cley West Bank specifically mapping the distribution of Eelgrass, Zostera, species. Survey was conducted to locate the eelgrass for future monitoring. Maps were hand drawn with OS grid references included. Natural England id: NATENG000232

Linear dataset showing the extent of National Trails. For more information visit the National Trails website. National Trails are long distance walking, cycling and horse riding routes through the best landscapes in England and Wales. There are 15 National Trails. Walkers can enjoy them all, cyclists and horse riders can enjoy the Pennine Bridleway and the South Downs Way, as well as sections of the other Trails. In total, England and Wales have around 2,500 miles (4,000 Km) of National Trail. The England Coast Path will be the newest (and longest) National Trail when it is complete in 2020. Full metadata can be viewed on data.gov.uk.

A new version of this dataset exists. To see the last version of the Antarctic Digital Database, have a look here: https://data.bas.ac.uk/collections/e74543c0-4c4e-4b41-aa33-5bb2f67df389/

Coastline for Antarctica created from various mapping and remote sensing sources, provided as polygons with ''land'', ''ice shelf'', ''ice tongue'' or ''rumple'''' attribute. Covering all land and ice shelves south of 60S. Suitable for topographic mapping and analysis. High resolution versions of ADD data are suitable for scales larger than 1:1,000,000. The largest suitable scale is changeable and dependent on the region.

Major changes in v7.5 include updates to ice shelf fronts in the following regions: Seal Nunataks and Scar Inlet region, the Ronne-Filchner Ice Shelf, between the Brunt Ice Shelf and Riiser-Larsen Peninsula, the Shackleton and Conger ice shelves, and Crosson, Thwaites and Pine Island. Small areas of grounding line and ice coastlines were also updated in some of these regions as needed.

Data compiled, managed and distributed by the Mapping and Geographic Information Centre and the UK Polar Data Centre, British Antarctic Survey on behalf of the Scientific Committee on Antarctic Research.

The South Wight Maritime European Marine Site (SWS EMS) is comprised of a variety of different types of reef including chalk, limestone, sandstone, clay / mudstone, greensand bedrock and boulder reefs, along with a number of sea caves and sea cave complexes. This high diversity of habitats is of considerable value as they support a high diversity of marine communities and therefore the diversity of the whole site. condition. This dataset is derived from a report commissioned by Natural England to assess the condition of intertidal rocky shore communities as a sub feature of the Reefs as well as the intertidal sea cave communities.

Coastline for area between 50degS and 60degS. Data published to support the Antarctic Digital Database (ADD) web map visualisation. South Georgia and the South Sandwich Islands taken from the South Georgia GIS (https://sggis.gov.gs/). All other data from Natural Earth ''Land'' and ''Minor Islands'' v4.1.0 1:10m scale shapefiles (https://www.naturalearthdata.com/). Data compiled, managed and distributed by the Mapping and Geographic Information Centre, British Antarctic Survey.

This dataset contains a mosquito species table with counts for adults and larvae. Samples are from twelve UK wetland sites, sampled between April 2017 and September 2018. A map included in the documentation included with this data shows site locations, which include both coastal and inland wetlands, and range from Devon to Kent and from Lincolnshire to Dorset. Samples were collected by staff from University of Greenwich and the UK Health Security Agency: collaborators in a NERC-funded project (NE/NO13379/1), part of the Valuing Nature Programme. We found a total of 19 mosquito species: • 10 Aedes • 3 Anopheles • 3 Culisseta • 2 Culex • 1 Coquillettidia

This map shows the extents of the various datasets comprising the World Elevation dynamic (Terrain, TopoBathy) and tiled (Terrain 3D, TopoBathy 3D, World Hillshade, World Hillshade (Dark)) services.The map has pop-ups defined. Click anywhere on the map to reveal details about the data sources.Topography sources listed in the table below are part of Terrain, TopoBathy, Terrain 3D, TopoBathy 3D, World Hillshade and World Hillshade (Dark), while bathymetry sources are part of TopoBathy and TopoBathy 3D only. Data Source Native Pixel Size Approximate Pixel Size (meters) Coverage Primary Source Country/Region

Topography

Australia 1m 1 meter 1 Partial areas of Australia Geoscience Australia Australia

Moreton Bay, Australia 1m 1 meter 1 Moreton Bay region, Australia Moreton Bay Regional Council Australia

New South Wales, Australia 5m 5 meters 5 New South Wales State, Australia DFSI Australia

SRTM 1 arc second DEM-S 0.0002777777777779 degrees 31 Australia Geoscience Australia Australia

Burgenland 50cm 0.5 meter 0.5 Burgenland State, Austria Land Burgenland Austria

Upper Austria 50cm 0.5 meter 0.5 Upper Austria State, Austria Land Oberosterreich Austria

Austria 1m 1 meter 1 Austria BEV Austria

Austria 10m 10 meters 10 Austria Geoland Austria

Canada HRDEM 1m 1 meter 1 Partial areas of the southern part of Canada Natural Resources Canada Canada

Canada HRDEM 2m 2 meters 2 Partial areas of the southern part of Canada Natural Resources Canada Canada

Denmark 40cm 0.4 meter 0.4 Denmark SDFE Denmark

Denmark 10m 10 meters 10 Denmark SDFE Denmark

England 2m 2 meters 2 70 % of England Environment Agency England

Estonia 1m 1 meter 1 Estonia Estonian Land Board Estonia

Estonia 5m 5 meters 5 Estonia Estonian Land Board Estonia

Estonia 10m 10 meters 10 Estonia Estonian Land Board Estonia

Finland 2m 2 meters 2 Finland NLS Finland

Finland 10m 10 meters 10 Finland NLS Finland

Berlin 1m 1 meter 1 Berlin State, Germany Geoportal Berlin Germany

Hamburg 1m 1 meter 1 Hamburg State, Germany LGV Hamburg Germany

Nordrhein-Westfalen 1m 1 meter 1 Nordrhein-Westfalen State, Germany Land NRW Germany

Sachsen-Anhalt 2m 2 meters 2 Sachsen-Anhalt State, Germany LVermGeo LSA Germany

Hong Kong 50cm 0.5 meter 0.5 Hong Kong CEDD Hong Kong SAR

Italy TINITALY 10m 10 meters 10 Italy INGV Italy

Japan DEM5A *, DEM5B * 0.000055555555 degrees 5 Partial areas of Japan GSI Japan

Japan DEM10B * 0.00011111111 degrees 10 Japan GSI Japan

Latvia 1m 1 meter 1 Latvia Latvian Geospatial Information Agency Latvia

Latvia 10m 10 meters 10 Latvia Latvian Geospatial Information Agency Latvia

Latvia 20m 20 meters 20 Latvia Latvian Geospatial Information Agency Latvia

Lithuania 1m 1 meter 1 Lithuania NZT Lithuania

Lithuania 10m 10 meters 10 Lithuania NZT Lithuania

Netherlands (AHN3/AHN4) 50cm 0.5 meter 0.5 Netherlands AHN Netherlands

Netherlands (AHN3/AHN4) 10m 10 meters 10 Netherlands AHN Netherlands

New Zealand 1m 1 meter 1 Partial areas of New Zealand Land Infromation New Zealand (Sourced from LINZ. CC BY 4.0) New Zealand

Northern Ireland 10m 10 meters 10 Northern Ireland OSNI Northern Ireland

Norway 10m 10 meters 10 Norway NMA Norway

Poland 1m 1 meter 1 Partial areas of Poland GUGIK Poland

Poland 5m 5 meters 5 Partial areas of Poland GUGIK Poland

Scotland 1m 1 meter 1 Partial areas of Scotland Scottish Government et.al Scotland

Slovakia 10m 10 meters 10 Slovakia GKÚ Slovakia

Slovenia 1m 1 meter 1 Slovenia ARSO Slovenia

Madrid City 1m 1 meter 1 Madrid city, Spain Ayuntamiento de Madrid Spain

Spain 2m (MDT02 2019 CC-BY 4.0 scne.es) 2 meters 2 Partial areas of Spain IGN Spain

Spain 5m 5 meters 5 Spain IGN Spain

Spain 10m 10 meters 10 Spain IGN Spain

Varnamo 50cm 0.5 meter 0.5 Varnamo municipality, Sweden Värnamo Kommun Sweden

Canton of Basel-Landschaft 25cm 0.25 meter 0.25 Canton of Basel-Landschaft, Switzerland Geoinformation Kanton Basel-Landschaft Switzerland

Grand Geneva 50cm 0.5 meter 0.5 Grand Geneva metropolitan, France/Switzerland SITG Switzerland and France

Switzerland swissALTI3D 50cm 0.5 meter 0.5 Switzerland and Liechtenstein swisstopo Switzerland and Liechtenstein

Switzerland swissALTI3D 10m 10 meters 10 Switzerland and Liechtenstein swisstopo Switzerland and Liechtenstein

OS Terrain 50 50 meters 50 United Kingdom Ordnance Survey United Kingdom

3DEP 1m 1 meter 1 Partial areas of the conterminous United States, Puerto Rico USGS United States

NRCS 1m 1 meter 1 Partial areas of the conterminous United States NRCS USDA United States

FEMA LiDAR DTM 3 meters 3 Partial areas of the conterminous United States FEMA United States

NED 1/9 arc second 0.000030864197530866 degrees 3 Partial areas of the conterminous United States USGS United States

3DEP 5m 5 meters 5 Alaska, United States USGS United States

NED 1/3 arc second 0.000092592592593 degrees 10 conterminous United States, Hawaii, Alaska, Puerto Rico, and Territorial Islands of the United States USGS United States

NED 1 arc second 0.0002777777777779 degrees 31 conterminous United States, Hawaii, Alaska, Puerto Rico, Territorial Islands of the United States; Canada and Mexico USGS United States

NED 2 arc second 0.000555555555556 degrees 62 Alaska, United States USGS United States

Wales 2m 2 meters 2 70 % of Wales Natural Resources Wales Wales

WorldDEM4Ortho 0.00022222222 degrees 24 Global (excluding the countries of Azerbaijan, DR Congo and Ukraine) Airbus Defense and Space GmbH World

SRTM 1 arc second 0.0002777777777779 degrees 31 all land areas between 60 degrees north and 56 degrees south except Australia NASA World

EarthEnv-DEM90 0.00083333333333333 degrees 93 Global N Robinson,NCEAS World

SRTM v4.1 0.00083333333333333 degrees 93 all land areas between 60 degrees north and 56 degrees south except Australia CGIAR-CSI World

GMTED2010 7.5 arc second 0.00208333333333333 degrees 232 Global USGS World

GMTED2010 15 arc second 0.00416666666666666 degrees 464 Global USGS World

GMTED2010 30 arc second 0.0083333333333333 degrees 928 Global USGS World

Bathymetry

Canada west coast 10 meters 10 Canada west coast Natural Resources Canada Canada

Gulf of Mexico 40 feet 12 Northern Gulf of Mexico BOEM Gulf of Mexico

MH370 150 meters 150 MH370 flight search area (Phase 1) of Indian Ocean Geoscience Australia Indian Ocean

Switzerland swissBATHY3D 1 - 3 meters 1, 2, 3 Lakes of Switzerland swisstopo Switzerland

NCEI 1/9 arc second 0.000030864197530866 degrees 3 Puerto Rico, U.S Virgin Islands and partial areas of eastern and western United States coast NOAA NCEI United States

NCEI 1/3 arc second 0.000092592592593 degrees 10 Partial areas of eastern and western United States coast NOAA NCEI United States

CRM 1 arc second (Version 2) 0.0002777777777779 degrees 31 Southern California coast of United States NOAA United States

NCEI 1 arc second 0.0002777777777779 degrees 31 Partial areas of northeastern United States coast NOAA NCEI United States

CRM 3 arc second 0.00083333333333333 degrees 93 United States Coast NOAA United States

NCEI 3 arc second 0.00083333333333333 degrees 93 Partial areas of northeastern United States coast NOAA NCEI United States

USGS CoNED 1 - 3 meters 1, 2, 3 Partial coastal areas of eastern and western United States USGS United States

GEBCO 2021 ** 0.00416666666666666 degrees 464 Global GEBCO World

GEBCO 2014 0.0083333333333333 degrees 928 Global GEBCO World * Fundamental Geospatial Data provided by GSI with Approval Number JYOU-SHI No.1239 2016. ** GEBCO Compilation Group (2021) GEBCO 2021 Grid (doi:10.5285/c6612cbe-50b3-0cff-e053-6c86abc09f8f) *** Bathymetry datasets are part of TopoBathy and TopoBathy3D services only.Disclaimer: Data sources are not to be used for navigation/safety at sea and in air.

Multibeam sonar data obtained from The United Kingdom Hydrography Office (UKHO) and ground-truthing information gathered from field surveys were used to train models and produce predictive habitat maps of kelp distribution along ~19 km stretch of coastline in Southern England. Bathymetric derivatives (roughness and fractal dimension) were used alongside acoustic backscatter intensity and depth as environmental variables for predictive modelling using a generalised boosting model (GBM).

The GEBCO_2020 Grid is a global continuous terrain model for ocean and land with a spatial resolution of 15 arc seconds. In regions outside of the Arctic Ocean area, the grid uses as a base Version 2 of the SRTM15_plus data set (Tozer, B. et al, 2019). This data set is a fusion of land topography with measured and estimated seafloor topography. Included on top of this base grid are gridded bathymetric data sets developed by the four Regional Centers of The Nippon Foundation-GEBCO Seabed 2030 Project. The GEBCO_2020 Grid represents all data within the 2020 compilation. The compilation of the GEBCO_2020 Grid was carried out at the Seabed 2030 Global Center, hosted at the National Oceanography Centre, UK, with the aim of producing a seamless global terrain model. Outside of Polar regions, the gridded bathymetric data sets supplied by the Regional Centers, as sparse grids, i.e. only grid cells that contain data were populated, were included on to the base grid without any blending. The data sets supplied in the form of complete grids (primarily areas north of 60N and south of 50S) were included using feather blending techniques from GlobalMapper software. The GEBCO_2020 Grid has been developed through the Nippon Foundation-GEBCO Seabed 2030 Project. This is a collaborative project between the Nippon Foundation of Japan and the General Bathymetric Chart of the Oceans (GEBCO). It aims to bring together all available bathymetric data to produce the definitive map of the world ocean floor by 2030 and make it available to all. Funded by the Nippon Foundation, the four Seabed 2030 Regional Centers include the Southern Ocean - hosted at the Alfred Wegener Institute, Germany; South and West Pacific Ocean - hosted at the National Institute of Water and Atmospheric Research, New Zealand; Atlantic and Indian Oceans - hosted at the Lamont Doherty Earth Observatory, Columbia University, USA; Arctic and North Pacific Oceans - hosted at Stockholm University, Sweden and the Center for Coastal and Ocean Mapping at the University of New Hampshire, USA.

The GEBCO_2021 Grid is a global continuous terrain model for ocean and land with a spatial resolution of 15 arc seconds. In regions outside of the Arctic Ocean area, the grid uses as a base, Version 2.2 of the SRTM15+ data set between latitudes of 50 degrees South and 60 degrees North. This data set is a fusion of land topography with measured and estimated seafloor topography. This version of SRTM15+ is similar to version 2.1 [Tozer et al., 2020] with minor updates. Version 2.2 uses predicted depths based on the V29 gravity model [Sandwell et al., 2019] and approximately 400 small areas containing suspect data were visually identified and removed from the grid. Included on top of this base grid are gridded bathymetric data sets developed by the four Regional Centers of The Nippon Foundation-GEBCO Seabed 2030 Project. The GEBCO_2021 Grid represents all data within the 2021 compilation. The compilation of the GEBCO_2021 Grid was carried out at the Seabed 2030 Global Center, hosted at the National Oceanography Centre, UK, with the aim of producing a seamless global terrain model. Outside of Polar regions, the gridded bathymetric data sets are supplied by the Regional Centers as sparse grids, i.e. only grid cells that contain data were populated, were included on to the base grid without any blending. The data sets supplied in the form of complete grids (primarily areas north of 60N and south of 50S) were included using feather blending techniques from GlobalMapper software. The primary GEBCO_2021 grid contains land and ice surface elevation information - as provided for previous GEBCO grid releases. In addition, for the 2021 release a version with under-ice topography/bathymetry information for Greenland and Antarctica is also available. The GEBCO_2021 Grid has been developed through the Nippon Foundation-GEBCO Seabed 2030 Project. This is a collaborative project between the Nippon Foundation of Japan and the General Bathymetric Chart of the Oceans (GEBCO). It aims to bring together all available bathymetric data to produce the definitive map of the world ocean floor by 2030 and make it available to all. Funded by the Nippon Foundation, the four Seabed 2030 Regional Centers include the Southern Ocean - hosted at the Alfred Wegener Institute, Germany; South and West Pacific Ocean - hosted at the National Institute of Water and Atmospheric Research, New Zealand; Atlantic and Indian Oceans - hosted at the Lamont Doherty Earth Observatory, Columbia University, USA; Arctic and North Pacific Oceans - hosted at Stockholm University, Sweden and the Center for Coastal and Ocean Mapping at the University of New Hampshire, USA.