This data set was acquired with a Kongsberg model EM120 multibeam sonar system during Nathaniel B. Palmer expedition NBP0401 conducted in 2004 (Chief Scientist: Dr. Terry Wilson). These data files include Sidescan, Swath Bathymetry, Acoustic Backscatter data and were processed at sea using the open source MB-System multibeam sonar processing software. These data are included in the GMRT Synthesis, beginning with version 2.0. Data were acquired as part of the project(s): Neotectonic Structure of Terror Rift, Western Ross Sea, and funding was provided by the U.S. National Science Foundation.