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_V09, titled "Valuing Australia’s new Gascoyne Marine Park." The voyage took place between 0000 November 19, 2022 and 0700 December 19, 2022 (UTC), departing from Fremantle and returning to Fremantle. 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 [range] m, throughout the voyage including within the Gascoyne and Ningaloo Marine Parks. All frequencies were logged continuously for the extent of the voyage. The 38 & 70 were periodically set to passive for the during the voyage to optimise MBES seabed mapping data quality. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 2344 files totalling 73 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 RV Investigator voyage IN2024_V04, 'Linking East Australian Current dynamics and submarine canyon geomorphology to marine ecosystem hotspots' which departed Sydney on the Friday 7th June and returned to Brisbane on the Wednesday 3rd July. 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 Sydney and Brisbane, with primary mapping focused on Richmond and Solitary Canyons. If the bottom was deeper than 1500 m during the camera operations the logging range was extended to capture the full water column. All frequencies were logged sporadically for the extent of the voyage as to not interfere with the ADCP which took priority over the EK60/EK80 to fulfil the voyage objectives. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 312 files totalling 28.4 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 IN2023_V03, SOTS: Southern Ocean Time Series automated moorings for climate and carbon cycle studies southwest of Tasmania which departed Hobart on May 12, 2023 and returned to Hobart on the May 25, 2023. 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 Hobart, the SOTS location and while on site. All frequencies were logged continuously for the extent of the voyage. There was a dedicated acoustic survey over the Patience Seamount while transiting to SOTS and also some opportunistic noise data collection to compare EK60 and EK80 noise levels. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 1130 files totalling 53 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_V07, [FOCUS] which departed Hobart on the 15/11/23 and returned to Hobart on the 20/12/23. 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 1500 m, around the Antarctic Circumpolar Current in the Southern Ocean, South of Hobart. All frequencies were logged continuously for the extent of the voyage. The 33 KHz and 70 KHz frequencies were set to passive for periods of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 1806 files totalling 176 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 IN2023_V04, International nutrient inter-comparison Voyage (INIV) which departed Hobart on the 05/06/23 and returned to Hobart on the 18/06/23. 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 1500 m, in the Southern Ocean Southwest of Hobart. All frequencies were logged sporadically for the extent of the voyage. The 70 KHz frequency was set to passive for the periods of the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 2,644 files totalling 59.6 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_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_E01, 'Sea Trials and Calibrations' which departed Fremantle on the 06/01/2023 and returned to Fremantle on the 12/01/2023 (UTC). 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 [range] m, around offshore Perth. All frequencies were logged continuously for the extent of the voyage. The frequencies were set to passive for the whole o the voyage. Data are stored in .raw, .bot and *.idx format at CSIRO. There are 106 files totalling 519 MB 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.