Data were collected by third-year students on a KSA324 field excursion down the D'Entrecasteaux Channel, on the IMAS vessel Noctiluca. The purpose of the trip was for students to learn how to collect various common types of oceanographic data and work on a research vessel. The study was designed to assess the impact of finfish farming in the Channel on local nutrient levels and water quality. The Tasmanian Environment Protection Authority (EPA) methods for water quality monitoring around finfish farms (Ford 2021, p. 6 – 18) were replicated as closely as possible. The null hypothesis for this study was that, on the 17/04/2023, all measured physico-chemical and biological factors were not significantly above the levels specified by the EPA guidelines (Ford 2021, p. 6 – 18), in any of the four stations measured. These four stations were chosen because they were all further than 35 metres beyond the boundary of any finfish farms’ Lease Area, as specified by the EPA guidelines document (Ford 2021, p. 6). The precise latitudes and longitudes of these stations are as follows: M1 (-43.059295, 147.345047); M2 (-43.056057, 147.291386); M3 (-43.123841, 147.290882); M4 (-43.133534, 147.326519). The dataset includes measurements of temperature, conductivity, oxygen concentration, pH, turbidity, fluorescence and pressure taken by the CTD rosette. Depth, density, practical salinity, absolute salinity and conservative temperature were derived and also included. The dataset also contains bottle sample measurements of oxygen, pH and alkalinity, as well as both the total and dissolved concentrations of ammonia, NOx, nitrite, phosphate and silicate. Chlorophyll concentration, total plankton cell counts, and counts of only Gymnodinium catenatum (a toxic, invasive dinoflagellate) cells were also included in the dataset. The dataset also contains the Secchi depth at each station. Empty cells are indicated by “NA”. ODV data flagging convention was used: 0 = good quality; 1 = unknown quality; 4 = questionable quality; 8 = bad quality. Reference: Ford, W (Director for the Environment Protection Authority) 2021, Environmental Licence No. 9869/3, Environmental Licence under the Environmental Management and Pollution Control Act 1994, pp. 6 – 18.