This report benefited from critical reviews by Seth Ackerman, Matthew Arsenault, and VeeAnn Cross (all of the U.S. Geological Survey). We would also like to thank Brian Todd of the Geological Survey of Canada for assisting us with our quest to find Canadian digital bathymetric data, Herman Varma for answering our questions regarding the tidal corrections concerning the Northwest Atlantic dataset, and Ole Hestvik for providing us with the most recent data from the Olex three-dimensional chart system. Special thanks to Dan Sampson of the Massachusetts Office of Coastal Zone Management for reviewing the finished digital elevation model.