Created from the Extracted Vector Shoreline Series, a topologically clean shoreline file depicting the Mean High Water line at the best scale for the continental U.S., Hawaii, Alaska, and U.S. territories. These data are available as a free 55 MB Download.

See http://nauticalcharts.noaa.gov/csdl/ctp/Merged_Vector_Shoreline.zip

The main purpose of the Charted Vector Shoreline Project is to provide public access to accurate and current coastline and shoreline data. The project targets scales between 1:10,000 and 1:80,000 with emphasis on the larger scales. Using processes and software designed by the Cartographic and Geospatial Technology Programs (CGTP), the vector data are automatically extracted from the NOAA Nautical Charts.

From each chart, Mean High Water and Mean Lower Low Water lines are extracted as vector lines from the binary raster files used in nautical chart production. The resulting vector high and lower low water lines are derived from the legal depictions on nautical charts for the United States. The resulting line files are checked for accuracy and converted from paper-charted units to geographic positions and imported to the shape file format used in GIS (Geographic Information Systems) applications.

The Mean High Water Line is represented by files with "gd20" in the name, and Mean Low Water Lines by files with "mar" in the name, for example 1276gd20.shp and 1276mar.shp respectively. Federal Geographic Data Committee (FGDC) compliant metadata is also available. The FGDC metadata file is a static file available online.

The Coastal Map Data Layer for GIS Systems project, designed to create an up-to-date, digital, and geo-referenced coastal map data layer, began as a way to provide the coastal stewardship community and general public with non-proprietary navigational chart images to be used as backdrops for Geographic Information Systems (GIS) derived products. Coastal maps are produced from NOS nautical charts for all near-shore geographic areas of the United States.

The nautical chart contains information critical to navigational users, but which obstructs a clear view of the basic topographic and hydrographic data. The charts are therefore cleaned of all navigational aides and symbols, prepared as TIF images and geo-referenced. Federal Geographic Data Committee (FGDC) compliant metadata is also available.

http://nauticalcharts.noaa.gov/csdl/ctp/cm_vs.htm

Source: NOAA