Maximum values of the settling volume and dry weight of suspended particulate matter, were found in the open waters of the southern Drake Passage (between 60°8' S and 62° 11' S), and west of the Anvers Island. Minimum respective values were observed in the Bransfield Strait. The distribution of phytoplankton cell numbers and of algal biomass expressed as total cell volumes closely followed the distribution of particulate matter. Diatoms were the major algae of the plankton. Several species of the genera Chaetoceros, Nitzschia and Corethron were dominant and characteristic of the phytoplankton assemblages in different parts of the study area.