This data set was acquired with a ship-based SeaBeam 2112 Multibeam Sonar system during Nathaniel B. Palmer expedition NBP9909 conducted in 1999 (Chief Scientist: Dr. John Bengtson). These data files are of MBSystem Compatible format and include Swath Bathymetry and Acoustic Backscatter 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): Antarctic Pack Ice Seals, and funding was provided by NSF grant(s): OPP98-15961.