The first comprehensive survey of basic physico-chemical water quality parameters along the South African coastline was carried out from 2016 to 2017, at more than 200 sampling sites. The west coast (Port Nolloth to Cape Town) was sampled 3 times, to establish seasonal variability associated with upwelling. The south- and east coasts (Cape Town to Sodwana) was sampled twice, to capture the influence of river runoff during high versus low river runoff conditions. The data can be used to assist with the revision of existing Water Quality Guidelines, which at present is inadequate due to a lack of comprehensive baseline data for these water quality parameters. The data also suggest areas of concern and that may be prone to land-based sources of pollution and eutrophication, and acidification, that will be discussed in more detail in manuscripts to be finalised.