This dataset contains the processed Hydrology (HYD) data collected on Franklin voyage FR 04/91. The voyage took place in the Bass Strait and off the NSW coast during 2-23 May 1991. This dataset has been processed and is archived within the CSIRO Marine and Atmospheric Research Data Centre in Hobart. Additional information regarding this dataset is contained in the cruise report for this voyage and/or the data processing report (as available). Franklin on-voyage hydrology data are typically obtained from water samples collected in Niskin bottles at various depths during each CTD cast. Parameters measured normally comprise temperature, salinity, dissolved oxygen, phosphate, nitrate, silicate and nitrite. The salinity data for this voyage had been identified as suspect. Following a review by the principal investigators in October 2006, the salnity data has been declared OK. More details are available to administrators via the MarLIN edit interface under "Author's comments".