This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2021_V01, "Quantifying krill abundance for krill monitoring and management off the Australian Antarctic Territory", which departed Hobart on the 29th January 2021 and returned to Hobart on the 24th March 2021 (AEST). The Simrad EK80 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a maximum range of 1500 m between Hobart and near Mawson station, Antarctica. All frequencies were logged continuously for the extent of the voyage. Acquisition settings (pulse length, power) were varied for the transit and survey portions of the voyage according to science requirements. Specific settings for each time period can be obtained from the GSM voyage report. From 1 Feb, 2021 the 18kHz WBT was replaced with the 18kHz GPT which was run for the remainder of the voyage. A calibration was performed at the survey location on 13 Feb 2021. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 3192 files totalling 295 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 IN2019_E01, 'Post-Dry Dock Calibration Trials', which departed Singapore on the 19th July 2019 and returned to Cairns] on the 2nd August 2019. EK60 Calibration data was also collected on this voyage 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, within Australia's EEZ in the Arafura sea, the Torres Strait and the Coral Sea. All frequencies were logged continuously for the extent of the voyage within Australia's EEZ. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 173 files totalling 15.9 GB of raw data in this dataset. Processing has been conducted on the calibration data only. 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 IN2017_C02, ['Hogan Group Hydrographic Survey – Bass Strait'] which departed Hobart on the 4th May 2017 and came alongside Bell Bay following completion of the survey on the 14th May 2017. The Simrad EK60 split beam echosounders [12], 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of [range] m, around Bass Strait. 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 1,120 files totalling 22 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 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 from the Marine National Facility (MNF) RV Investigator Voyage IN2020_V08, titled "SOLACE - Southern Ocean Large Areal Carbon Export: quantifying carbon sequestration in subpolar and polar waters." The voyage took place between December 5, 2020 and January 16, 2021 departing from Hobart (TAS) and arriving in Hobart (TAS). The Simrad EK80 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m, at the three study locations and transit to and from Hobart . All frequencies were logged continuously for the extent of the voyage. Logging of "complex samples" occurred daily for one hour. Data are stored in *.raw (6273 files 625 GB) and *.idx (6273 files 63.0 MB) formats at CSIRO. 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 IN2020_V09 (SOTS: Southern Ocean Time Series automated moorings for climate and carbon cycle studies southwest of Tasmania), which departed Hobart on the 27th August 2020 and returned to Hobart on the 12th September 2020. In addition to the tasks at the SOTS site the voyage also recovered a Rintoul mooring that was deployed during IN2020_V05. The Simrad EK80 wide band transceivers (WBT) 18, 38, 70, 120, 200 and 333 kHz, as well as the EK60 split-beam GPT 18kHz were used to acquire acoustic backscatter data to a range of 1500 m, during the voyage. All frequencies were logged sporadically (only when transiting) for the extent of the voyage. The frequencies were set to passive for the periods when stationary during the voyage. Note: the EK80 18kHz WBT failed at 12:06 on the 28th August 2020 (UTC) and was no longer used for the voyage. The 18kHz transducer was changed over to the EK60 GPT for the remainder of the voyage (in place of the 18kHz WBT). Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 291 files totalling 27.7 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 IN2018_E02, titled 'MNF Trials and Calibrations' which departed Hobart on the 3rd of September 2018 and returned to Hobart on the 9th of September 2018. The Simrad EK60 split beam echosounders [12], 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 4000 m, around south eastern Tasmania. EK60 calibration data was loaded into EK80 software for all settings to verify calibration values obtained from the EK60 real time calibration routine. Ek80 was also used to analyse the coverage of the four higher frequencies when just using the files for the 18kHz and the 38kHz. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 107 files totalling 1.1 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 IN2018_T01, titled: "Physical and biogeochemical gradients in the East Australian Current." The voyage took place from Hobart (TAS) to Brisbane (QLD) between April 5 and April 14, 2018. The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data, between Brisbane and Hobart. 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 2,175 files totalling 41.7 GB of raw data in this dataset. No processing has been conducted on this data. Data spans 5/04/2018 20:00 until 06/04/2018 06:00 UTC. 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 IN2020_E01 (Trials and Calibration) which departed Hobart on the 29th July 2020 and returned to Hobart on the 6th August 2020. The purpose of this voyage was to undertake post port-period equipment calibrations and commissioning, sea trials and personnel training. The Simrad EK80 wide band transceivers (WBT) 18, 38, 70, 120, 200 and 333 kHz and the EK60 split-beam GPT 333 kHZ were calibrated at the start of this voyage at anchor in the Derwent Estuary on July 29, 2020. The EK80 WBTs were calibrated using default settings for both CW and FM modes. The EK80 system was then used to acquire acoustic backscatter data to a range of 1500 m for the remainder of the voyage offshore to the southeast of Tasman Peninsula. The EK60 split-beam GPTs for 18, 70, 120 and 200kHz were calibrated at anchor in the Derwent Estuary at the end of the voyage on August 6th, 2020. All frequencies were logged sporadically for the extent of the voyage. The frequencies were set to passive for periods during the voyage when conducting other system calibrations. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 1,061 files totalling 99.9 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_E02, which departed Hobart 2015-04-07 and returned on 2015-04-14. This voyage is a trial of the new vessel for conducting benthic biological sampling. The Simrad EK60 split beam echosounder was turned on for testing. No processing or QC has been conducted on this data. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 161 files totalling 19.5 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.