This data set was acquired with a Kongsberg model EM120 multibeam sonar system during Nathaniel B. Palmer expedition NBP0709 conducted in 2007 (Chief Scientist: Dr. Stephen Ackley). These data files include Acoustic Backscatter, Sidescan, Swath Bathymetry 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 with funding provided by the U.S. National Science Foundation.