This dataset contains a time-series of oceanographic data collected at the 50m coastal station off Rottnest Island, Western Australia (lat. 32 deg. 00 min. S, long. 115 deg. 25 min. E). The station was set up under the CSIRO coastal monitoring programme in the 1950s and is sampled for temperature, salinity, dissolved oxygen, nitrate and silicate at depths of 0, 10, 20, 30, 40 and 50m below the surface. Sampling is undertaken at monthly intervals from April 1951 and continued until July 2002, after which the sampling regime was irregular. The data are stored on-line as part of the CMR hydrology archive in Hobart and are available via the CMAR Data Trawler see link below. Since April 2009 the sampling became part of the IMOS program. The current sampling regime is approximately monthly for 11 or 12 months per year. The IMOS sampling includes additional Biological data. The ongoing data is currently available via the IMOS portal. Please see Data Links below. Additional copies of the data up to 1989 are deposited with the NODC data archive (World Data Centre-A) in the U.S.A., and details of relevant data files can be viewed via their website by requesting the file inventory for this coastal station which is NODC platform code "09K2". Station details, plus printed versions of the data up to the end of 1960, have been published in CSIRO's "Oceanographical Station List" series.