This data set was acquired with a SeaBeam Instruments model 2112 multibeam sonar system during Nathaniel B. Palmer expedition NBP9805 conducted in 1998 . These data files include 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 1. Data were acquired while the Nathaniel B. Palmer was in transit.