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 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 IN2022_V06, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27 degrees South." The voyage took place between July 14 and July 30, 2022 (AEST), departing from Brisbane and returning to Brisbane. 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 1,500 m, around Brisbane 27 degrees South. All frequencies were logged continuously for the extent of the voyage, except when asked to switch off for mooring activities. Occasionally, the 70kHz & 120kHz frequencies were set to passive for the periods of shallow mapping with EM710, and ADCP interference requests from the chief scientist, but all other frequencies wer set to active during the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 877 files totalling 40 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 IN2023_V06, titled: "Understanding Eddy Interactions and Their Impacts In the East Australian Current System." The voyage took place between October 9 and November 2, 2023, departing from Sydney (NSW) and returning to Sydney. 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 1500m, around NSW/VIC coastal areas. All frequencies were logged continuously for the extent of the voyage. The 70kHz & 120kHz frequencies were set to passive for the periods of shallow mapping areas of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 394 files totalling 35.6 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 IN2018_V06, which departed Hobart on the 22-Nov-2018 and returned to Hobart on the 19-Dec-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 [range] m, Huon, Tasman Fracture Marine Parks and the St Helens seamount, Tasmania.. All frequencies were logged continuously for the extent of the voyage The frequencies were] set to passive for the periods when tracking towed bodies using USBL. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 4690 files totalling 90 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 IN2016_T02, transit from Hobart to Sydney which departed Hobart on the 25 August 2016 and arrived in Sydney on the 29 August 2016. The Simrad EK60 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 Sydney. All frequencies were logged continuously for the extent of the transit. Data are stored in .raw, .bot and *.idx format at CSIRO Oceans and Atmosphere. There are 432 lines totaling 10.1 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 IN2023_E03, titled "Trials & Calibrations", which was segmented into 3 legs, departing Hobart on September 13 and ending in Sydney on September 30, 2023. Leg 1 (Hobart to Hobart) took place between 13-16 Sep, Leg 2 (Hobart to Hobart) between 16-25 Sep and Leg 3 (Hobart to Sydney) between 26-30 Sep. The Simrad EK80 wide band transceivers (WBT) 38, 70, 120, 200 kHz and the EK60 split-beam GPT 18 kHz were calibrated during Leg 2 of the voyage. The calibration was undertaken at anchor in the Derwent Estuary on September 18, 2023 with the 38mm sphere deployed at 03:00 (UTC) and calibration recording conducted between 07:14 - 10:06 (UTC). The EK80 WBTs were calibrated using default settings for only CW modes. Due to line snagging issues under the hull and resulting time limitations, no calibration was undertaken for the 333 kHz or for the remaining EK60 GPTs. The results of the calibration were not applied immediately to the EK80 (pending further onshore analysis). 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 or during shallow water mapping when interference was noted on the mapping system (EM710) from the 70 and 120kHz frequencies mainly. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 519 files totalling 45.6 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 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 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.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2021_E01 (Trials and Calibration) which departed Hobart on the 10th November 2021 and returned to Hobart on the 14th November 2021. The purpose of this voyage was to undertake annual 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 18, 70, 120, 200 and 333 kHz were calibrated at the start of this voyage at anchor in the Derwent Estuary on the 10th November 2021. 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. 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 289 files totalling 25.7 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.