This is a MD iMAP hosted service. Find more information at http://imap.maryland.gov. These are shoal boundaries off the coast of Maryland created by the Maryland Geological Survey (MGS). No formal metadata was received - but MGS describes the data as generalized polygon outlines - mostly qualitative assessments of where the thickness of the sand body pinches out to less than 1 meter thickness over the underlying revinement surface. In some cases it is the 60 foot contour - where there is no seismic data.Feature Service Link:http://geodata.md.gov/imap/rest/services/Geoscientific/MD_OceanShoal/FeatureServer/0 ADDITIONAL LICENSE TERMS: The Spatial Data and the information therein (collectively "the Data") is provided "as is" without warranty of any kind either expressed implied or statutory. The user assumes the entire risk as to quality and performance of the Data. No guarantee of accuracy is granted nor is any responsibility for reliance thereon assumed. In no event shall the State of Maryland be liable for direct indirect incidental consequential or special damages of any kind. The State of Maryland does not accept liability for any damages or misrepresentation caused by inaccuracies in the Data or as a result to changes to the Data nor is there responsibility assumed to maintain the Data in any manner or form. The Data can be freely distributed as long as the metadata entry is not modified or deleted. Any data derived from the Data must acknowledge the State of Maryland in the metadata.