This record describes multibeam echosounder data collected from the Marine National Facility (MNF) RV Investigator Voyage IN2020_V01, titled: “Development of William’s Ridge, Kerguelen Plateau: tectonics, hotspot magmatism, microcontinents, and Australia’s Extended Continental Shelf” between January 08 and March 06, 2020 departing from Henderson (WA) and returning back to Fremantle (WA). The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter at Rig Seismic Seamount, Williams Ridge, Broken Ridge and on associated transits. 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 2164 files totalling 174 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, and processed bathymetry and backscatter grids in geotiff 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 echo sounder data collected during field experiments on RV South Cape survey SC2020_V01. CSIRO’s Oceans & Atmosphere Shallow Survey Facility (SSF) undertook multibeam water column experiments over an artificial seep deployed near Kingston Beach, southern Tasmania. The goal of the experiments was to characterize the utility of high frequency multibeam water column data for the detection of gas seeps in very shallow water (<20 m). These experiments were aligned to inform the ANLEC R&D Carbon Capture and Storage Marine Monitoring and Verification (MM&V) project (ANLEC R&D 7-0816-0305) on the application of multibeam water column data for the detection of gas seeps in shallow water as a regular monitoring tool. The Geophysical Survey & Mapping team single-head EM2040C multibeam was mobilised on RV South Cape and bathymetry and water column data were collected over a custom-built bubble release system to simulate a shallow water gas seep at a test site near Kingston Beach, southern Tasmania. The EM2040 provides a 1.3° by 1.3° transmit and receive angular resolution respectively. Data were acquired at 300kHz frequency using single swath mode, short CW pulse, beam spacing set at equidistant and sector coverage set to 65° port and starboard (total coverage 130°). Data are stored in *.all raw format for bathymetry and backscatter and in *.wcd format for water column backscatter at the CSIRO. There are 397 *.all and 373 *.wcd files totaling 129 GB of raw multibeam data in this dataset. Sound velocity profiles were applied to the data during data acquisition. Bathymetry data contained in *.all format have been corrected for motion and position. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report (sc2020_v01_Bubble_experiments_CCS_Rev_1.pdf). Water column data were post-processed using custom MATLAB workflows. A variety of workflow methods were tested, with the processing results of each available in *.txt and *.jpg format. Additional data products may be available on request.

This record describes magnetometer data collected on RV Investigator voyage 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 SeaSPY2 magnetometer uses an omnidirectional Overhauser sensor that requires no realignment or recalibration and has no heading error. The instrument has an absolute accuracy of 0.1 nT, sensor sensitivity of 0.01 nT and resolution of 0.001 nT. Data are stored in .CSV and .MMS data files at CSIRO. 0.68 MB of raw data was acquired in this dataset. No processing has been conducted on this data. The magnetometer was towed 300 m astern of the ship and a layback value of 361 m was applied to the magnetometer data. This was the total distance behind the ship's positioning reference point. Note: The magnetometer was only deployed for a short period (between 23:04 & 23:51 on the 03/08/2020 - UTC) for training purposes only. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes magnetometer data collected on RV Investigator voyage IN2022_V08, titled "Biodiversity Assessment of Australia’s Indian Ocean Territories", which departed Darwin on September 30 and returned to Fremantle on November 3, 2022. This was a continuation of voyage IN2021_v04. The SeaSPY2 magnetometer uses an omnidirectional Overhauser sensor that requires no realignment or recalibration and has no heading error. The instrument has an absolute accuracy of 0.1 nT, sensor sensitivity of 0.01 nT and resolution of 0.001 nT. Data are stored in .CSV and .MMS data files at CSIRO. 92 MB of raw data was acquired in this dataset. No processing has been conducted on this data. The magnetometer was towed ~300 m astern of the ship and a layback value of 361 was applied to the magnetometer data. This was the total distance behind the ship's positioning reference point. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes magnetometer data collected on 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 May 25, 2023. The SeaSPY2 magnetometer uses an omnidirectional Overhauser sensor that requires no realignment or recalibration and has no heading error. The instrument has an absolute accuracy of 0.1 nT, sensor sensitivity of 0.01 nT and resolution of 0.001 nT. Data are stored in .CSV and .MMS data files at CSIRO. 34.0MB of raw data was acquired in this dataset. No processing has been conducted on this data. The magnetometer was towed 300 m astern of the ship and a layback value of 361 m was applied to the magnetometer data. This was the total distance behind the ship's positioning reference point. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes magnetometer data collected on RV Investigator voyage IN2020_V06, titled "Probing the Australian-Pacific Plate Boundary: Macquarie Ridge in 3-D." The voyage took place between October 8 and November 3, 2020 departing from Hobart (TAS) and arriving in Hobart (TAS). The SeaSPY2 magnetometer uses an omnidirectional Overhauser sensor that requires no realignment or recalibration and has no heading error. The instrument has an absolute accuracy of 0.1 nT, sensor sensitivity of 0.01 nT and resolution of 0.001 nT. Data are stored in .CSV and .MMS data files at CSIRO. 219 MB of raw data was acquired in this dataset. No processing has been conducted on this data. The magnetometer was towed 300 m astern of the ship and a layback value of 361 m was applied to the magnetometer data. This was the total distance behind the ship's positioning reference point. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes sub bottom profiler data collected on RV Investigator voyage IN2017_V05, 'Long-term recovery of trawled marine communities 25 years after the world's largest adaptive management experiment', which departed Broome on the 11 October 2017 and returned to Henderson on the 10 November 2017. The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. The SBP120 was logged continuously for the extent of the voyage. Data are stored in *.raw 998 files 130 GB raw and *.segy 998 files 130 GB segy formats at CSIRO. The segy format data had a real time processing stream applied, which applies a seabed mute, a bandpass or matched filter dependent on pulse type, and a time variable gain. All *segy files were processed using Seismic Unix. The segy files are converted to *.su format, projected using suutm, trace shifted using sushift and the source coordinates copied to the group coordinates. The su data are written back to segy with utm zone number stored in byte 21 and group coordinates in byte locations 81 and 85. 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 magnetometer data collected on RV Investigator voyage IN2024_T01, 'Transit Voyage: Fremantle to Hobart.' The primary objective of the voyage was the safe and timely transit of RV Investigator from Fremantle to Hobart in preparation for the following research voyage. During the transit various research projects were conducted, along with outreach, familiarisation and training activities. The voyage departed Fremantle on the 09 March and returned to Hobart on the 20 March. The SeaSPY2 magnetometer uses an omnidirectional Overhauser sensor that requires no realignment or recalibration and has no heading error. The instrument has an absolute accuracy of 0.1 nT, sensor sensitivity of 0.01 nT and resolution of 0.001 nT. Data are stored in .CSV and .MMS data files at CSIRO. 132 MB of raw data was acquired in this dataset. No processing has been conducted on this data. The magnetometer was towed 300 m astern of the ship and a layback value of 376 m was applied to the magnetometer data. This was the total distance behind the ship's positioning reference point. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes sub bottom profiler data collected from the Marine National Facility (MNF) RV Investigator Voyage IN2020_V01, titled: “Development of William’s Ridge, Kerguelen Plateau: tectonics, hotspot magmatism, microcontinents, and Australia’s Extended Continental Shelf” between January 08 and March 06, 2020 departing from Henderson (WA) and returning back to Fremantle (WA). The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. The SBP120 was logged continuously for the extent of the voyage. Data are stored in *.raw (972 files 17.7 GB) raw and *.seg (996 files 18.2 GB) segy formats at CSIRO. The segy format data had a real time processing stream applied, which applies gain, a gain correction, matched filter with replica shaping, an attribute calculation for instantaneous amplitude and time variable gain. 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 sub bottom profiler data collected on RV Investigator voyage IN2018_C01, 'RAN Hydrographic Survey' which departed Hobart on the 28th May 2018 and returned to Hobart on the 8th June 2018. The overall focus for this survey was to conduct a modern survey in the primary shipping route through Bass Strait and to facilitate safe navigation for international and coastal shipping. The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. The SBP120 was logged continuously for the extent of the voyage. Data are stored in *.raw (155 files 10.8 GB) raw and *.seg (156 files 10.9 GB) segy formats at CSIRO. The segy format data had a real time processing stream applied, which applies gain, a gain correction, matched filter with replica shaping, an attribute calculation for instantaneous amplitude and time variable gain. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request