The data set comprises measurements of temperature, salinity, oxygen, chlorophyll and nutrients from six locations near Port Erin, Isle of Man. The data collected at Port Erin breakwater (54 05.113N, 04 46.083W) and the Cypris station in Port Erin Bay (54 05.5N, 004 50.0W) are described separately in the "Port Erin (Isle of Man, Irish Sea) Temperature, Salinity and Nutrient Data Set (1904-)". The remaining four stations are described here. Data have been collected at the Resa (also known as Bayrnagh), approximately 5km east of Santon Head, Isle of Man (54 05.00N, 04 30.00W) at least once per month since 1994, with a hiatus from 2003-2006. The data comprise measurements of temperature at 0, 5, 10, 20 and 37m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 37m; and chlorophyll-a at the surface. Total dissolved nitrogen was also measured at 0 and 37m between 1996 and 2003, while total dissolved phosphorus was measured at 0 and 37m between 1996 and June 2002. Corresponding data have been collected at Laxey Bay (54 12.00N, 04 23.00W), Ramsey Bay (54 20.47N, 04 17.47W) and Jurby Head Targets area (54 21.50N, 04 38.00W) at least once a month since 2006. Laxey Bay data comprise temperature at 0, 5, 10, 20 and 24m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 24m; and chlorophyll-a at the surface. Ramsey Bay data comprise temperature at 0, 5, 10 and 19m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 19m; and chlorophyll-a at the surface. Targets data comprise temperature at 0, 5, 10, 20 and 43m; salinity, dissolved oxygen, phosphate, nitrate, nitrite, silicate and ammonia at 0 and 24m; and chlorophyll-a at the surface. Prior to 2006 water samples and temperature measurements were collected using either a Nansen-Pettersen bottle with an insulated thermometer or an NIO bottle with a mercury reversing thermometer. Since 2006 an NIO bottle and a Sensoren Instrumente Systeme (SIS) RTM 4002 X digital deep sea reversing thermometer have been used. Salinity was determined by titration against silver nitrate until 1965, thereafter using inductively coupled salinometers (Plessey 6230N until June 1998; Guildline Portasal from July 1998). Nutrients are estimated colorimetrically and dissolved oxygen is determined by the Winkler technique, as outlined in Jacobsen et al. (1950). Until 2006, chlorophyll-a was estimated using the trichromatic methods recommended by SCOR-UNESCO Working Group 17. Since that year the spectroscopic methods of Aminot & Rey (2000) have been used. Dissolved nitrogen and dissolved phosphorus were measured using the persulphate digestion method adapted from Valderama (1981). The data were collected by the Port Erin Marine Laboratory (part of the University of Liverpool) until its closure in 2006. Sampling has since been taken over by the Isle of Man Government Laboratory (GAL). The data are managed by the British Oceanographic Data Centre.