This record describes multibeam echosounder data collected on Bluefin voyage BF2018_V01, 'Hydrographic survey of the Petuna Aquaculture Sites in SW Bass Strait' which departed Stanley, Tasmania on the 27th June 2018 and returned to Beauty Point, Tasmania on the 4th July 2018. This survey was a part of a broader mapping campaign that involved a survey of the Boags Commonwealth Marine Reserve. The Kongsberg EM2040c multibeam echosounder was used to acquire seafloor bathymetry and backscatter information and watercolumn backscatter at the Boags Marine Reserve in the Bass Strait. The EM2040c provides a 1.3° by 1.3° transmit and receive angular resolution respectively. The echosounder's nominal frequency was 300 kHz and was operated in dual swath mode. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. There are 269 files totalling 73.6 GB of raw .all data, and 269 files totalling 0.64Tb of raw .wcd in this combined campaign dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. Tide corrections were not applied to the final processed dataset. Instead the data was mapped to the ellipsoid (GPS Height) and thereafter reduced to AHD (Australian Height Datum) using the AusGeoid09 model. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry and backscatter grids in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing reports. Additional data products may be available on request.