Benthic Macrofauna Sampling Data used to construct benthic habitat maps for FIIS. Data were collected during ground-truth surveys involving the collection of surficial grab samples of the seafloor and sediment profile imagery (SPI). Grab samples for analysis of macrofaunal community structure were collected in triplicate within Otis Pike and Sunken Forest to allow for more robust statistical analyses and to account for small-scale spatial variability that may be present. Single grab samples were taken at each site within East Breach to allow for a broader distribution of sample sites throughout the area. All samples were processed on board the vessel at the time of collection to ensure quality of data and avoid sample degradation. Each sample was sieved through a 0.5 mm mesh and captured macrofauna were retained and preserved in a Rose-Bengal solution to be processed at a designated lab. All individuals were counted and identified to the species level. SPI images were collected to corroborate and complement the acoustic and grab sample data. Images were taken at each grab sample site and also along a series of planned transects designed to cross boundaries identified in the sidescan mosaics. All deployments of the camera were done in triplicate, resulting in six images per site (one deployment of the camera captures two images ten seconds apart).