The biomass and percentage cover of subtidal macro algae were recorded at five sites near Anvers Island, along the Antarctic Peninsula (64°S, 64°W) in 1989. Total macroalgal wet biomass ranged from 1.64 to 6.34 kg m−2. The largest biomass contributors were the large overstory brown algae (Phaeophyceae) Desmarestia antarctica Moe et Silva, Desmarestia menziesii J. Agardh, Desmarestia anceps Montagne and Himantothallus grandifolius (Skottsberg) Zinova. These species had an overall cover of 72% of the bottom. D. menziesii and/or D. anceps were dominant at 2 and 5 m. D. antarctica dominated the overstory at 10 and 15 m. H. grandifolius was also abundant at 15 m and dominated at 20 m. Several red macroalgae (Rhodophyta) were also conspicuous: Iridaea cordata (Turner) Bory and Curdiea racovitzae Hariot at 2 and 5 m; Myriogramme mangini (Gain) Skottsberg and Plocamium cartilagineum (Linnaeus) Dixon at 10 and 15 m; and Gigartina skottsbergii Setchell et Gardner and Sarcodia montagneana (Hooker et Harvey) J. Agardh at 15 and 20 m. The presence of large quantities of epilithic D. antarctica at 10 and 15 m was very unusual, as this species has previously been described as an obligate epiphyte with a depth distribution restricted to <10 m.