What Lies Beneath
Coast Survey conducts surveys of the ocean floor, creating detailed hydrographic maps of depths and
features. These data are used to create raster and electronic nautical charts.
Hydrographic survey vessels utilize both a multibeam sonar and towed side scan sonar to map the sea floor.
Hydrographic Survey Data
The National Centers for Environmental
Information (NCEI) maintains the digital data archive for all
hydrographic data of the coastal waters and exclusive economic zone of the United States and its
territories collected by Coast Survey. The database provides hydrographic survey products which contain
additional details of the ocean floor not shown on the nautical charts. NCEI is also a scientific
steward for other sources of bathymetric
and ocean depth data collected by other agencies.
Historic Survey Data
Coast Survey's historic maps and charts are available from the following portals:
- Bathymetry and fishing maps: Download detailed contour maps of U.S. waters and the Great Lakes. These maps have
not been updated since 1990 but they may provide detail of the seafloor, and are useful for fishing
and undersea exploration.
- Coast Survey Historical Map & Chart Collection:
Every prior edition of every chart in the Coast Survey catalog is available, dating back hundreds of
years. These charts include historic features, such as LORAN-C lines.
Additional Resources for Offshore Data
Side scan imagery helps find and identify features on the seafloor, like this underwater wreck.
Many other U.S. government agencies and private organizations collect data on the ocean floor such as:
- NOAA's Digital Coast: Repository of spatial data including, lidar and benthic data.
- U.S. Geological Survey coastal and marine geology: Detailed seafloor maps, useful for identifying undersea erosion, shoreline change, faults, and movement of sediment and pollutants.
- U.S. Army Corps of Engineers (USACE): USACE are responsible for surveying much of the U.S. inland waterways and ship channels. Each district maintains their own database of survey sheets. Select a location and district to find files available for download.
- MarineCadastre.gov: The Bureau of Energy Management and NOAA, in cooperation with federal and state partners created the GIS-based marine information data viewer for U.S. waters which has expanded into an integrated marine information website.
- SeaSketch: A collaborative site for ocean planners, stakeholders, and the public for marine spatial planning.