The National Bathymetric Source (NBS) project creates and maintains high-resolution bathymetry composed of the best available data. This project enables the creation of next-generation nautical charts while also providing support for modeling, industry, science, regulation, and public curiosity. Primary sources of bathymetry include NOAA and U.S. Army Corps of Engineers hydrographic surveys and topographic bathymetric (topo-bathy) lidar (light detection and ranging) data. Data submitted through the NOAA Office of Coast Survey’s external source data process are also included, with gaps in deep water filled through Global Multi-Resolution Topography, a merged model of bathymetry. Different vertical datums and file formats are made available to meet various uses. The BlueTopo folder includes multilayer floating point GeoTIFFs with associated Raster Attribute Tables (RAT) containing elevation, vertical uncertainty, with other quality metrics and source information. These files are arranged in a spatial tiling and resolution scheme corresponding to the Electronic Navigational Chart (ENC) but are not for navigation due to the inclusion of additional non-navigation data and non-navigation vertical datums. For navigational datasets please see the S-102 distribution portal. "nowCOAST" provides public access to BlueTopo through the nowCOAST viewer, web map tile services (WMTS), and links to individual datasets.

THIS MAP IS NOT AUTHORITATIVE. SEE TERMS OF USE BELOW.This web map was developed by the National Oceanic and Atmospheric Administration’s (NOAA) Office for Coastal Management and is featured in the U.S. Great Lakes Collaborative Benthic Habitat Mapping Common Operating Dashboard in support of the Collaborative Benthic Habitat Mapping in the Nearshore Waters of the Great Lakes Basin Project. This multi-year, multi-agency project is funded through the Great Lakes Restoration Initiative (GLRI) and focuses on new bathymetric data (airborne lidar and vessel based sonar) acquisition, validation, and benthic habitat characterization mapping of the nearshore waters (0-80 meters) in the U.S. Great Lakes. This project also contributes to the regional Lakebed 2030 campaign, which aims to have high-density bathymetric data available for the entirety of the Great Lakes by 2030. This web map contains data layers reflecting the current status of bathy data coverage in the nearshore (0-80 meters) of the U.S. Great Lakes, including acquisition (lidar and multibeam sonar), ground-truthing/validation, and benthic habitat mapping and characterization. Acquisition layers include coverage areas that have been acquired and are available for public use (green) as well as those that have been acquired, but are not yet available or are still in progress (orange). The nearshore water depth layers (0-25 and 25-80 meters) were created using the National Centers for Environmental Information (NCEI) Great Lakes Bathymetry (3-second resolution) grid extracts. The 0 to 25 meter nearshore water depth layer represents areas where bathymetric lidar data acquisition could ideally be conducted, depending on water condition and turbidity. The 25 to 80 meter layer shows locations where acoustic data acquisition can occur. See below for information on additional data layers. All data originally projected in the following coordinate system: EPSG:3175, NAD 1983 Great Lakes and St Lawrence Albers.This map will continue to be updated as new information is made available.Source Data for Bathy Coverage Layers - Acquired/Available:Topobathy and Bathy Lidar (NOAA's Data Access Viewer: https://coast.noaa.gov/dataviewer/#/; U.S. Interagency Elevation Inventory (USIEI): https://coast.noaa.gov/inventory/). Multibeam Sonar (National Centers for Environmental Information (NCEI) Bathymetric Data Viewer: https://www.ncei.noaa.gov/maps/bathymetry/; NOAA's Data Access Viewer: https://coast.noaa.gov/dataviewer/#/; U.S. Interagency Elevation Inventory (USIEI): https://coast.noaa.gov/inventory/; USGS ScienceBaseCatalog: https://www.sciencebase.gov/catalog/item/656e229bd34e7ca10833f950)Source Data for Bathy Coverage Layers - GLRI AOIs (2020-2024):Acquisition: NOAA Office for Coastal ManagementValidation/CMECS Characterizations: NOAA National Centers for Coastal Ocean Science (NCCOS)Source Data for Bathy Coverage Layers - In Progress and Planned:NOAA Office of Coast Survey Plans: https://gis.charttools.noaa.gov/arcgis/rest/services/Hydrographic_Services/Planned_Survey_Areas/MapServer/0NOAA Office for Coastal ManagementSource Data for Nearshore Water Depths:NOAA's National Centers for Environmental Information (NCEI) Great Lakes Bathymetry (3-second resolution) grid extracts: https://www.ncei.noaa.gov/maps/grid-extract/Source Data for Spatial Prioritization Layers:Great Lakes Spatial Priorities Study Results Jun 2021. https://gis.charttools.noaa.gov/arcgis/rest/services/IOCM/GreatLakes_SPS_Results_Jun_2021/MapServerMapping priorities within the proposed Wisconsin Lake Michigan National Marine Sanctuary (2018). https://gis.ngdc.noaa.gov/arcgis/rest/services/nccos/BiogeographicAssessments_WILMPrioritizationResults/MapServerThunder Bay National Marine Sanctuary Spatial Prioritization Results (2020). https://gis.ngdc.noaa.gov/arcgis/rest/services/nccos/BiogeographicAssessments_TBNMSPrioritizationResults/MapServerSource Data for Supplemental Data Layers:International Boundary Commission U.S./Canada Boundary (version 1.3 from 2018): https://www.internationalboundarycommission.org/en/maps-coordinates/coordinates.phpNational Oceanic and Atmospheric Administration (NOAA) HydroHealth 2018 Survey: https://wrecks.nauticalcharts.noaa.gov/arcgis/rest/services/Hydrographic_Services/HydroHealth_2018/ImageServerNational Oceanic and Atmospheric Administration (NOAA) Marine Protected Areas (MPA) Inventory 2023-2024: https://www.fisheries.noaa.gov/inport/item/69506National Oceanic and Atmospheric Administration (NOAA) National Marine Sanctuary Program Boundaries (2021): https://services2.arcgis.com/C8EMgrsFcRFL6LrL/arcgis/rest/services/ONMS_2021_Boundaries/FeatureServerNational Oceanic and Atmospheric Administration (NOAA) U.S. Bathymetry Gap Analysis: https://noaa.maps.arcgis.com/home/item.html?id=4d7d925fc96d47d9ace970dd5040df0aU.S. Environment Protection Agency (EPA) Areas of Concern: https://services.arcgis.com/cJ9YHowT8TU7DUyn/arcgis/rest/services/epa_areas_of_concern_glahf_viewlayer/FeatureServerU.S. Geological Survey (USGS) Great Lakes Subbasins: https://www.sciencebase.gov/catalog/item/530f8a0ee4b0e7e46bd300dd Latest update: February 20, 2025

A 1/3 arc-second Mean Lower Low Water bathymetric DEM of NOS hydrographic survey data in Charlotte Harbor.

A map service showing the location and coverage derived from NOAA's National Ocean Service (NOS), Office of Coast Survey (OCS) Hydrographic Surveys in U.S. waters and non-hydrographic surveys acquired external to OCS, that have been assessed by OCS for use in NOAA’s navigational products and the National Bathymetry. The NOS Hydrographic Database (NOSHDB) and Hydrographic Survey Metadata Database (HSMDB), both maintained by NOS and NOAA's National Centers for Environmental Information (NCEI), provide extensive survey coverage and ISO metadata of the coastal waters and Exclusive Economic Zone (EEZ) of the United States and its territories. The NOSHDB contains digitized data from smooth sheets of hydrographic surveys completed between 1837 and 1965, and from survey data acquired digitally on NOS survey vessels since 1965. Data products from NOS surveys and others assessed by NOS, including Bathymetric Attributed Grid (BAG) files, Descriptive Reports, smooth sheet images, survey data images, textual gridded data, and geo-referenced sidescan sonar mosaics, ISO metadata, and survey statistics are available for download from NCEI.Modern surveys provide gridded data in the form of bathymetric attributed grids (BAGs). Please see the following services for mosaics of the BAG data:Bathymetric Attributed Grid (BAG) Image Service (provides depth values).Bathymetric Attributed Grid (BAG) shaded relief visualization image service (color shaded relief).Layers available in this map service:Layer 0: All Surveys with Digital Data: Combining both Surveys with BAGs and Surveys with Digital Sounding Data, this layer describes all bathymetric data collected for NOAA's Office of Coast Survey in a usable digital format as either gridded surface data or xyz point soundings.Layer 1: Surveys with BAGs: This layer includes hydrographic data from ~1995 to the present. A Bathymetric Attributed Grid (BAG) is an open sourced file format for storing and exchanging bathymetric data developed by the Open Navigation Surface Working Group. BAG files are gridded, multi-dimensional bathymetric data files and are the standard NOS hydrographic data file for public release.Layer 2 (hidden by default): Surveys without Digital Data: This layer includes historical hydrographic data from as early as the 1800s. Smooth Sheet images exist for these historical depth soundings that have not been digitized into an xyz format. Smooth Sheets are the final, neatly drafted, accurate plot of verified and corrected bathymetric data based on the method collected and are available as Tagged Image File Format (TIFF), Multi-resolution Seamless Image Database (MrSID) format, or as a geo-referenced PDF.The NCEI Bathymetric Data Viewer (NOAA GeoPlatform entry) can be used to search and display these data. More information about NOS Hydrographic Survey data available at NCEIAlso see the NOS Seabed Descriptions from Hydrographic Surveys Map Service.ISO collection-level metadata for NOS Hydrographic Surveys

Digital terrain models (DTMs) produced from multibeam bathymetric data provide valuable base maps for marine geological interpretations. These maps help define the geological variability of the seafloor (one of the primary controls of benthic habitat diversity); improve our understanding of the processes that control the distribution and transport of bottom sediments, and the distribution of benthic habitats and associated infaunal community structures; and provide a detailed framework for future research, monitoring, and management activities. The bathymetric survey interpreted herein (National Oceanic and Atmospheric Administration (NOAA) survey H11255) covers roughly 95 km2 of seafloor in southeastern Long Island Sound. This bathymetry has been examined in relation to seismic reflection data collected concurrently, as well as archived seismic profiles acquired as part of a long-standing geologic mapping partnership between the State of Connecticut and the U.S. Geological Survey (USGS). The objective of this work was to use these acoustic data sets to interpret geomorphological attributes of the seafloor, and to use these interpretations to better understand the Quaternary geologic history and modern sedimentary processes.

A 1/3 arc-second Mean Lower Low Water bathymetric DEM of NOS hydrographic survey data in Indian River, FL.

A color shaded relief visualization of the General Bathymetric Chart of the Oceans GEBCO_2024 grid, combined with generalized land cover coloration from the Natural Earth 1 dataset. The Natural Earth 1 imagery and lake polygons were obtained from https://naturalearthdata.com. The coastline displayed is from Esri's World Countries dataset.Please also see NOAA/NCEI's layer of GEBCO bathymetric contours.A grayscale version is also available, and see here for a map with both hillshade and contours included.

This tile layer displays detailed color shaded relief visualizations of high-resolution quality-controlled seafloor elevation from NOAA National Ocean Service (NOS) Hydrographic Survey Bathymetric Attributed Grids (BAGs) in U.S. coastal waters. Many near-shore areas have been mapped at high resolution (often 1 meter or better). The depths are usually relative to Mean Lower Low Water (MLLW) datum. BAG is a non-proprietary file format for storing and exchanging bathymetric data developed by the Open Navigation Surface Working Group. BAG files are gridded, multi-dimensional bathymetric data files and is the standard NOS hydrographic data file for public release. Current versions of the BAG file contain position and depth grid data, as well as position and uncertainty grid data, and the metadata specific to that BAG file, providing end users information about the source and contents of the BAG file. The corresponding NOS Hydrographic Surveys map service displays the locations and coverage of the hydrographic surveys as polygons, along with additional metadata and links to obtain the data. This image service is available in 3 versions:Tile Layer (overview of all surveys in a continuous image)Note: this is a tiled image service, cached to zoom level 15 (~4.7 m resolution).Dynamic Image Service (overview of all surveys in a continuous image)Subsets version (access to the underlying images; allows subsets using a definition query; maximum of 80 rasters displayed at a time)The NCEI Bathymetric Data Viewer can be used to search and display these data. More information about NOS Hydrographic Survey data available at NCEI.Below is the color scale used to represent depths (usually relative to Mean Lower Low Water): Last update: Nov. 8, 2024

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic DEMs are used to support tsunami forecasting and warning efforts at the NOAA Center for Tsunami Research, Pacific Marine Environmental Laboratory (PMEL). The DEMs are part of the tsunami forecast system SIFT (Short-term Inundation Forecasting for Tsunamis) currently being developed by PMEL for the NOAA Tsunami Warning Centers, and are used in the MOST (Method of Splitting Tsunami) model developed by PMEL to simulate tsunami generation, propagation, and inundation. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of North American Vertical Datum of 1988 (NAVD 88) or Mean High Water (MHW) and horizontal datum of World Geodetic System 1984 (WGS84). Cell size for the DEMs ranges from 1/3 arc-second (~10 meters) to 3 arc-seconds (~90 meters).

This image service provides access to gridded bathymetric products derived from multibeam data collected by the NOAA Ship Okeanos Explorer. The products were created from data collected on cruises starting in 2009 through the current field season. For the companion "seamless mosaic" image service providing depth values and options for visualization, please see Bathy Grids. For daily updates providing initial versions of bathymetric products, please see Near-Real-Time Bathy Grids.Surveys containing restricted data may or may not be included within this layer. Multibeam sonar data and products archived with NOAA National Center for Environmental Information (NCEI) are accessible through the NOAA Ocean Exploration Data Atlas, the Okeanos Explorer Data Landing Pages, and the Bathymetric Data Viewer. Data Visualization Tips:By default, the service provides a color shaded relief visualization of the depth values. Alternatively, the actual depth values in meters can be displayed by setting the processing template to "User Defined Renderer" in the ArcGIS Online layer using the "Image Display" menu, or in ArcMap under "Processing Templates: None".This service has several server-side raster functions available for data visualization. This can be selected in the ArcGIS Online layer using "Image Display", or in ArcMap under "Processing Templates".None (default): Provides depth values in meters.MultidirectionalHillshadeHaxby_8000-0: A color shaded relief visualization using Esri's "multidirectional hillshade". This is also available as a separate tiled service (faster to draw). The depths are displayed using this color ramp:MultidirectionalHillshadeHaxby_DRA: A color shaded relief visualization using Esri's "multidirectional hillshade". The color scale is automatically stretched to the min and max depth values visible in the current view (dynamic range adjustment). The depths are displayed using this color ramp.There are also similar visualizations available using different color ramps (blue, dark blue, purple-blue):Numerous bathymetric AGOL products exist for Okeanos Explorer. Please read the below descriptions to ensure proper usage:Bathy Coverage hosted feature layer provides polygons of where multibeam data were collected. This layer does not visually represent the data values.Bathy Grids imagery layer provides a seamless mosaic of gridded multibeam products. Bathy Grids (subsets) imagery layer is a slightly less optimized version of the previous layer but allows users to filter data based on Survey ID, etc. Near-Real-Time Bathy Grids imagery layer provides a seamless mosaic of provisional multibeam products delivered daily during ship operations. Data not yet archived at NCEI may also be found here prior to ingest.Bathy Grids (tiled color hillshade visualization) layer provides a more optimized data visualization that the previously listed imagery layers. This layer can be coupled with the below tiled elevation layer for 3D visualization within Esri Scenes. Bathy Grids (tiled elevation) layer provides an elevation mesh. Couple this layer with the above tiled color hillshade for 3D visualization within Esri Scenes. Please provide any feedback or questions to OER.info.mgmt@noaa.gov.

The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA), is producing detailed geologic maps of the coastal sea floor. Bathymetry, originally collected by NOAA for charting purposes, provides a fundamental framework for research and management activities along this part of Rhode Island Sound, shows the composition and terrain of the seabed, and provides information on sediment transport and benthic habitat. Interpretations were derived from the multibeam echo-sounder data collected in Rhode Island Sound. During July 2010, bottom photographs and surficial sediment data were acquired as part of a ground-truth reconnaissance survey of these areas. For more information on the ground-truth survey see http://quashnet.er.usgs.gov/data/2010/10033/.

A 180-m (6 arc-second) resolution gridded digital elevation model (DEM) grayscale hillshade for the bathymetry (ocean depth) of the Western Pacific Ocean surrounding the Mariana Trench, the deepest part of the Earth's oceans. The extent of the DEM encompasses not only the Mariana Trench, but also the West Mariana Ridge and the East Mariana Ridge, the island of Guam, and the Commonwealth of the Northern Mariana Islands (CNMI). It was compiled by the NOAA National Centers for Environmental Information (NCEI), formerly the National Geophysical Data Center (NGDC), from various data sources including international, federal, and academic partners. Not to be used for navigational purposes. For the related dataset containing numeric bathymetry values for this image layer, see http://pacioos.org/metadata/ngdc_bathy_180m_mariana.html

One of the National Geospatial-Intelligence Agency’s (NGA) and the National Oceanic and Atmospheric Administration’s (NOAA) missions is to ensure the safety of navigation on the seas by maintaining the most current information and the highest quality services for U.S. and global transport networks. To achieve this mission, we need accurate coastal bathymetry over diverse environmental conditions. The SCuBA program focused on providing critical information to improve existing bathymetry resources and techniques with two specific objectives. The first objective was to validate National Aeronautics and Space Administration’s (NASA) Ice, Cloud and land Elevation SATellite-2 (ICESat-2), an Earth observing, space-based light detection and ranging (LiDAR) capability, as a useful bathymetry tool for nearshore bathymetry information in differing environmental conditions. Upon validating the ICESat-2 bathymetry retrievals relative to sea floor type, water clarity, and water surface dynamics, the next objective is to use ICESat-2 as a calibration tool to improve existing Satellite Derived Bathymetry (SDB) coastal bathymetry products with poor coastal depth information but superior spatial coverage. Current resources that monitor coastal bathymetry can have large vertical depth errors (up to 50 percent) in the nearshore region; however, derived results from ICESat-2 shows promising results for improving the accuracy of the bathymetry information in the nearshore region.

Project Overview
One of NGA’s and NOAA’s primary missions is to provide safety of navigation information. However, coastal depth information is still lacking in some regions—specifically, remote regions. In fact, it has been reported that 80 percent of the entire seafloor has not been mapped. Traditionally, airborne LiDARs and survey boats are used to map the seafloor, but in remote areas, we have to rely on satellite capabilities, which currently lack the vertical accuracy desired to support safety of navigation in shallow water. In 2018, NASA launched a space-based LiDAR system called ICESat-2 that has global coverage and a polar orbit originally designed to monitor the ice elevation in polar regions. Remarkably, because it has a green laser beam, ICESat-2 also happens to collect bathymetry information ICESat-2. With algorithm development provided by University of Texas (UT) Austin, NGA Research and Development (R&D) leveraged the ICESat-2 platform to generate SCuBA, an automated depth retrieval algorithm for accurate, global, refraction-corrected underwater depths from 0 m to 30 m, detailed in Figure 1 of the documentation. The key benefit of this product is the vertical depth accuracy of depth retrievals, which is ideal for a calibration tool. NGA and NOAA National Geodetic Survey (NGS), partnered to make this product available to the public for all US territories. View the SCuBA Info Graphic
All details on how SCuBA was developed, how to access data, and how to use the data, please visit the DOCUMENTATION page.

A 1/3 arc-second Mean Lower Low Water bathymetric DEM of NOS hydrographic survey data in Tomales Bay.

The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA), is producing detailed geologic maps of the coastal sea floor. Bathymetry and sidescan-sonar imagery, originally collected by NOAA for charting purposes, provides a fundamental framework for research and management activities in Long Island Sound, shows the composition and terrain of the seabed, and provides information on sediment transport and benthic habitat. During October 2008 NOAA completed hydrographic survey H11251 offshore of Rocky Point, New York and during November 2009, bottom photographs and surficial sediment data were acquired as part of a ground-truth reconnaissance survey of this area. Interpretive data layers were derived from the multibeam echo-sounder and sidescan-sonar data and the ground-truth data used to verify them. For more information on the ground-truth survey see http://quashnet.er.usgs.gov/data/2009/09059/

The U.S. Interagency Elevation Inventory displays high-accuracy topographic and bathymetric data for the United States and its territories. The project is a collaborative effort between NOAA, the U.S. Geological Survey, the Federal Emergency Management Agency, the U.S. Department of Agriculture, the U.S. Forest Service, the National Park Service and the U.S. Army Corps of Engineers. This resource is a comprehensive, nationwide listing of known high-accuracy topographic data, including lidar and IfSAR, and bathymetric data,including NOAA hydrographic surveys, multibeam data, and bathymetric lidar. The following data layers are updated quarterly: topographic lidar, topobathy shoreline lidar, IfSAR data, and bathymetric lidar. The NOAA hydrographic surveys, the multibeam and trackline bathymetry shown are provided via a service that is available from the NOAA National Centers for Environmental Information (NCEI). Access the bathymetric data directly from the NCEI at: http://maps.ngdc.noaa.gov/viewers/bathymetry/ The US Army Corps of Engineers (USACE) hydrographic surveys are provided via a service that is available from the USACE. The information provided for each elevation dataset includes many attributes such as vertical accuracy, point spacing, and date of collection. A direct link to access the data or information about the contact organization is also available through the inventory.

Bathymetry is the measurement of the depth of the ocean floor, data that can be used for a variety of purposes such as: nautical charting, oceanographic research and modeling, habitat classification, maritime commerce, and recreational applications. The Multibeam Bathymetry Database (MBBDB) at NCEI collects and archives multibeam data from the earliest commercial installations (circa 1980) through today's modern high-resolution collections. Data are acquired from both U.S. and international government and academic sources (see individual cruise metadata records for source information) and consist of the raw (as collected) sonar data files. Datasets may also include processed or edited versions of the sonar data, ancillary data (i.e., sound velocity data), derived products (i.e., grids), and/or metadata for the data collection. The MBBDB provides data that span the globe and are discoverable and accessible via map interface or text-only search options. More information about the database can be found here.This ArcGIS image service provides a color shaded relief visualization of gridded multibeam data from the entire archive. Each individual survey has been gridded at a 3 arc-second cell size (~100m), divided into 10-degree tiles, then organized into an ArcGIS mosaic dataset. "Overviews" are then built upon the underlying tiles to provide a seamless raster that combines all the surveys. Where surveys overlap, the mean depth value of the contributing surveys is used.Note: NCEI's archive typically contains the raw, unedited multibeam data provided by the data contributors. There are some erroneous depth values and/or data artifacts visible in this service. These data should not be used for navigational purposes.There are three services providing access to the multibeam archive:Multibeam Bathymetry Mosaic (REST endpoint): provides depth values (default) or shaded-relief imagery. All surveys are combined together (using mean depth value) into "overviews".Multibeam Bathymetry Mosaic: Shaded Relief Visualization: tiled image service, provides rapid display of color shaded relief imagery.Multibeam Bathymetry Mosaic Subsets (REST endpoint): provides access to the individual surveys, and allows filtering by survey ID, platform name, source organization, survey date, etc. This service has slower performance than the others.This tiled service is also available as a downloadable tile package (.tpkx file) usable in ArcGIS Pro / ArcGIS Desktop software.For ship tracks of the multibeam surveys, along with additional metadata and links to obtain the data, see the corresponding Multibeam Bathymetric Surveys service.NCEI's Bathymetric Data Viewer (NOAA GeoPlatform entry) provides an interactive mapping interface to the multibeam database as well as other sources of bathymetric data.For visualization, the water depths are displayed using this color ramp:Mosaic last updated: Mar. 5, 2024.Metadata for the Multibeam Bathymetric Database

This dataset reports bathymetry data from Barataria Bay, Louisiana. NOAA National Geophysical Data Center (NGDC) bathymetry data used to build a computational grid of the northern Gulf of Mexico from April-August, 2010 is included.

A 1/3 arc-second Mean Lower Low Water bathymetric DEM of NOS hydrographic survey data in Galveston Bay.

NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions. These integrated bathymetric-topographic DEMs are used to support tsunami forecasting and modeling efforts at the NOAA Center for Tsunami Research, Pacific Marine Environmental Laboratory (PMEL). The DEMs are part of the tsunami forecast system SIFT (Short-term Inundation Forecasting for Tsunamis) currently being developed by PMEL for the NOAA Tsunami Warning Centers, and are used in the MOST (Method of Splitting Tsunami) model developed by PMEL to simulate tsunami generation, propagation, and inundation. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of Mean High Water (MHW) and horizontal datum of World Geodetic System 1984 (WGS84). Grid spacings for the DEMs range from 1/3 arc-second (~10 meters) to 3 arc-seconds (~90 meters).The DEM Global Mosaic is an image service providing access to bathymetric/topographic digital elevation models stewarded at NOAA's National Centers for Environmental Information (NCEI), along with the global GEBCO_2014 grid: http://www.gebco.net/data_and_products/gridded_bathymetry_data. NCEI builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness. This service is a general-purpose global, seamless bathymetry/topography mosaic. It combines DEMs from a variety of near sea-level vertical datums, such as mean high water (MHW), mean sea level (MSL), and North American Vertical Datum of 1988 (NAVD88). Elevation values have been rounded to the nearest meter, with DEM cell sizes going down to 1 arc-second. Higher-resolution DEMs, with greater elevation precision, are available in the companion NAVD88: http://noaa.maps.arcgis.com/home/item.html?id=e9ba2e7afb7d46cd878b34aa3bfce042 and MHW: http://noaa.maps.arcgis.com/home/item.html?id=3bc7611c1d904a5eaf90ecbec88fa799 mosaics. By default, the DEMs are drawn in order of cell size, with higher-resolution grids displayed on top of lower-resolution grids. If overlapping DEMs have the same resolution, the newer one is shown. Please see NCEI's corresponding DEM Footprints map service: http://noaa.maps.arcgis.com/home/item.html?id=d41f39c8a6684c54b62c8f1ab731d5ad for polygon footprints and more information about the individual DEMs used to create this composite view. In this visualization, the elevations/depths are displayed using this color ramp: http://gis.ngdc.noaa.gov/viewers/images/dem_color_scale.png.A map service showing the location and coverage of land and seafloor digital elevation models (DEMs) available from NOAA's National Centers for Environmental Information (NCEI). NCEI builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness. Layers available in the map service: Layers 1-4: DEMs by Category (includes various DEMs, both hosted at NCEI, and elsewhere on the web); Layers 6-11: NCEI DEM Projects (DEMs hosted at NCEI, color-coded by project); Layer 12: All NCEI Bathymetry DEMs (All bathymetry or bathy-topo DEMs hosted at NCEI).This is an image service providing access to bathymetric/topographic digital elevation models stewarded at NOAA's National Centers for Environmental Information (NCEI), with vertical units referenced to mean high water (MHW). NCEI builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness. This service provides data from many individual DEMs combined together as a mosaic. By default, the rasters are drawn in order of cell size, with higher-resolution grids displayed on top of lower-resolution grids. If overlapping DEMs have the same resolution, the newer one is shown. Alternatively, a single DEM or group of DEMs can be isolated using a filter/definition query or using the 'Lock Raster 'mosaic method in ArcMap. This is one of three services displaying collections of DEMs that are referenced to common vertical datums: North American Vertical Datum of 1988 (NAVD88): http://noaa.maps.arcgis.com/home/item.html?id=e9ba2e7afb7d46cd878b34aa3bfce042, Mean High Water (MHW): http://noaa.maps.arcgis.com/home/item.html?id=3bc7611c1d904a5eaf90ecbec88fa799, and Mean Higher High Water: http://noaa.maps.arcgis.com/home/item.html?id=9471f8d4f43e48109de6275522856696. In addition, the DEM Global Mosaic is a general-purpose global, seamless bathymetry/topography mosaic containing all the DEMs together. Two services are available: http://noaa.maps.arcgis.com/home/item.html?id=c876e3c96a8642ab8557646a3b4fa0ff Elevation Values: http://noaa.maps.arcgis.com/home/item.html?id=c876e3c96a8642ab8557646a3b4fa0ff and Color Shaded Relief: http://noaa.maps.arcgis.com/home/item.html?id=feb3c625dc094112bb5281c17679c769. Please see the corresponding DEM Footprints map service: http://noaa.maps.arcgis.com/home/item.html?id=d41f39c8a6684c54b62c8f1ab731d5ad for polygon footprints and more information about the individual DEMs used to create this composite view. This service has several server-side functions available. These can be selected in the ArcGIS Online layer using 'Image Display ', or in ArcMap under 'Processing Templates '. None: The default. Provides elevation/depth values in meters relative to the NAVD88 vertical datum. ColorHillshade: An elevation-tinted hillshade visualization. The depths are displayed using this color ramp: http://gis.ngdc.noaa.gov/viewers/images/dem_color_scale.png. GrayscaleHillshade: A simple grayscale hillshade visualization. SlopeMapRGB: Slope in degrees, visualized using these colors: http://downloads.esri.com/esri_content_doc/landscape/SlopeMapLegend_V7b.png. SlopeNumericValues: Slope in degrees, returning the actual numeric values. AspectMapRGB: Orientation of the terrain (0-360 degrees), visualized using these colors: http://downloads.esri.com/esri_content_doc/landscape/AspectMapLegendPie_V7b.png. AspectNumericValues: Aspect in degrees, returning the actual numeric values.