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. The bathymetry will provide elevations and show geomorphic characteristics of the seafloor, while the backscatter and acoustical backscatter imagery will enhance the geomorphic characteristics and give insight to variations of sediment types on the seafloor. This file is the 50-m cell size grid of the combined swath and single-beam bathymetry around Cat Island, Miss.