During 1985 and 1986, sublittoral communities on hard substrates in the southern Delta area, SW Netherlands, were investigated at 79 stations. The stations were distributed over 20 localities situated in the saline Lake Grevelingen, the Oosterschelde estuary and the SE North Sea. The percentage cover of all sessile organisms were estimated using quadrat sampling techniques; data were processed using cluster analysis. The stations were characterized by the assessment of the most important environmental parameters: available light, hydrodynamics and sediment characteristics. Eight sublittoral communities on hard substrates are described by characteristic and dominant species. Three communities are subdivided into variants on account of differences in abundance of the dominant species. This quantitative approach leads to reproduceable results.