In September and October of 2010, the U.S. Geological Survey (USGS), in cooperation with the Army Corps of Engineers (USACE), conducted geophysical surveys around Cat Island, Miss. to collect bathymetry, acoustical backscatter, and seismic reflection data (seismic-reflection data have been published separately, Forde and others, 2012). The geophysical data along with sediment vibracore data (yet to be published) will be integrated to analyze and produce a report describing the geomorphology and geologic evolution of Cat Island. Interferometric swath bathymetry, and acoustical backscatter data were collected aboard the RV G.K. Gilbert during the first cruise which took place September 7-15, 2010. Single-beam bathymetry was collected in very shallow water around the island aboard the RV Streeterville from September 28 through October 2, 2010 to bridge the gap between the landward limit of the previous cruise and the shoreline. The survey area extended from the nearshore to approximately 5 kilometers (km) offshore to the north, south, and west, and approximately 2 km to the east. This report archives bathymetry and acoustical backscatter data and provides information and mapping products essential for completion of the project goals. In order to comprehend seafloor surface lithology; acoustic backscatter mosaics, such as the data herein, are used as an aid in determining seafloor material types and extents. The file containing the backscatter data is a 1m GeoTIFF raster data set.