This data set was acquired with a Kongsberg model EM120 multibeam sonar system during Nathaniel B. Palmer expedition NBP0506 conducted in 2005 (Chief Scientist: Dr. Miles McPhee). 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. Data were acquired as part of the project(s): Maud rise Non-linear Equation of State Study, and funding was provided by the U.S. National Science Foundation.