Provides a description of the habitat mapping and groundtruthing efforts from side scan sonar surveys conducted in May 2004, June 2005, and April 2006 aboard the NOAA Ship McArthur II to obtain imagery of the Olympic Coast National Marine Sanctuary seafloor. Images were obtained in support of broader habitat mapping coverage of sanctuary waters, and to help delineate locations of suitable deep-sea coral/sponge habitat for revisiting and resurveying in more detail on subsequent cruises. Imagery was integrated with complementary data from a towed camera sled, ROVs, sedimentary samples, and bathymetry records to describe geological and biological aspects of habitat, and was used to create a preliminary map of various habitat polygon features for use in a geographical information system.