This record describes multibeam echosounder data collected on RV Investigator research charter IN2015_C01, 'GAB deep water geological and benthic ecology program,' which departed Hobart on the 25 October and returned to Port Lincoln on the 28 November. A short sea trial voyage (October 22 - 25, Hobart - Hobart) was undertaken prior to the charter. Data for those days is also included in this data set. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter. The EM122 provides a 1 degree by 1 degree angular resolution. The echosounder's nominal frequency is 12 kHz. Data are stored in .all raw format for bathymetry and backscatter and .wcd format for watercolumn backscatter at CSIRO. There are 1658 files totalling 58.5 GB of raw data in this 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 processed data. Processed data had outliers removed. Processed line data are available in *.gsf and ascii format. Additional information regarding this dataset, including information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes multibeam echosounder data collected on RV Investigator research charter, IN2015_C01, 'GAB deep water geological and benthic ecology program' which departed Hobart on the 25 October and returned to Port Lincoln on the 28 November. A short sea trial voyage (October 22 - 25, Hobart - Hobart) was undertaken prior to the charter. Data for those days is also included in this data set. The Kongsberg EM710 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter. The EM710 provides a 0.5° by 1° transmit and receive angular resolution respectively. The echosounder's nominal frequency range is from 70 to 100 kHz. Data are stored in .all raw format for bathymetry and backscatter and .wcd format for watercolumn backscatter at CSIRO. There are 65 files totalling 4.93 GB of raw data in this dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format is corrected for motion and position. Tide corrections were not applied to the processed data. Processed data 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 report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2018_V01, Detecting Southern Ocean change from repeat hydrography, deep Argo and trace element biogeochemistry & CAPRICORN which departed Hobart on the 11 January 2018 and returned to Hobart on the 22 February 2018. The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m, between Hobart and 66°S. All frequencies were logged continuously for the extent of the voyage but no personnel were on board to monitor the acquisition. Data are stored in .raw, .bot and .idx format at CSIRO. There are 1041 .raw files totalling 94.8 GB of raw data in this dataset. Processing has been conducted on this data for the return transit from 66S to Hobart.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2023_V05, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 1). The voyage took place between June 28, 2023 and July 30, 2023 (AEST), departing from Hobart and returning to Hobart. The Simrad EK60 split beam echosounders for 18kHz and Simrad EK80 split beam echosounders for 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500m, between Hobart and Sydney. All frequencies were logged continuously for the extent of the voyage. The 70 & 120 kHz frequencies were set to passive for periods of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 809 files totalling 68.4 GB of raw data in this dataset. No Processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2015_T01, which departed Hobart 2015-05-10 and arrived Sydney on 2015-05-13. This voyage was a three-day transit from Hobart to Sydney. There were no science personnel onboard, however some opportunistic bathymetric survey was undertaken in addition to a deployment of the Continuous Plankton Recorder. The Simrad EK60 split beam echosounder was turned on sporadically. No processing or QC has been conducted on this data. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 610 files totalling 14.8 GB of raw data in this dataset. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2023_V01, titled "Antarctic Bottom Water Production in the past: Records from marine sediments, Cape Darnley, East Antarctica". The voyage took place between 25th January, 2023 and 2nd March, 2023 departing from Henderson's (WA) and arriving in Hobart (TAS). The Simrad EK60 split beam echosounders for18kHz and Simrad EK80 split beam echosounders for 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1,500m, between Fremantle and Antarctica (one-way) and then from Albany to Hobart. All frequencies were logged continuously for the extent of the voyage. The 75kHz and 120kHz frequencies were set to passive for shallow areas where EM710 was used. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 1,143 lines totalling 106 GB of raw data in this dataset. No post processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2024_V03, titled "Untangling the causes of change over 25 years in the southeast marine ecosystem (SEA-MES Voyage 2)." The voyage took place between May 01, 2024 and May 31, 2024 (AEST), departing from Hobart and returning to Sydney. The Simrad EK60 split beam echosounders for 18kHz and Simrad EK80 split beam echosounders for 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m, between the shelf areas of eastern Australia from Hobart, TAS to Sydney, NSW. All frequencies were logged continuously for the extent of the voyage. The frequencies 70kHz & 120kHz were set to passive for small periods of mapping during the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 688 files totalling 64.3 GB of raw data in this dataset. No post processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2019_T02, titled: "Deep seascapes of the Great Barrier Reef: Uncovering submarine canyons and landslides." The voyage took place between October 4 and October 14, 2019 departing from Brisbane (QLD) and arriving in Darwin (NT). The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m, between Brisbane to Darwin transit. All frequencies were logged sporadically for the extent of the voyage. The frequencies were set to passive for the periods of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 728 files totalling 36 GB of raw data in this dataset. The EK60, EM122 and SBP120 were synchronised using K-Sync as often as possible to minimise cross-system interference. No p/Processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2015_C02, Great Australian Bight Research Program: GAB deep-water pelagic and benthic ecosystem study which departed Port Lincoln on the 30 November 2015 and returned to Fremantle on the 22 December 2015. The Simrad EK60 split beam echosounders 12, 18, 38, 70 120, 200 and 333 kHz frequencies were used to acquire acoustic backscatter data to a range of 1500 m, around the Great Australian Bight. All frequencies except for the 12 kHz were logged continuously for the extent of the voyage. The 12 kHz was logged for a portion of the voyage, but was also set to passive mode periodically. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 998 files totaling 83.7 GB of raw data in this dataset. Some processing has been conducted on this data, which will be available through IMOS. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the Marine National Facility (MNF) RV Investigator voyage IN2024_V02, titled "SOTS: Southern Ocean Time Series automated moorings for climate and carbon cycle studies southwest of Tasmania." The voyage took place between March 31, 2024 and April 19, 2024 (AEST), departing from Hobart and returning to Hobart. The Simrad EK60 split beam echosounders for 18kHz and Simrad EK80 split beam echosounders for 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m from Hobart to the SOTS moorings sites and during the return transit. All frequencies were logged continuously for the extent of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 783 files totalling 73.7 GB of raw data in this dataset. Calibration values from the IN2023_E03 calibration were applied on acquisition. IMPORTANT NOTE: The 18 kHz transducer had a faulty channel for the duration of this voyage. Although data was logged, the 18 kHz data should NOT be used for quantitative analysis. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.