Between late June and early December 1967, observations were made at numerous stations in McMurdo Sound in the Antarctic. This paper, dealing primarily with Sts. A and H in the Hut Point region, provides some new physico-chemical data on the ice habitat as well as information on the development of microalgal populations in the sea ice, data on levels of chlorophyll a and particulate carbon, and results of periodic laboratory measurements of C14 fixation.