Bryum cf. algens Card, was collected by SCUBA divers from 9-31 m in the benthos of perennially ice-covered Lake Vanda (77°32′S, 161°35′E), Wright Valley, southern Victoria Land, Antarctica. It occurred as a component of a microbial mat consisting primarily of Phormidium frigidum Fritsch, Lyngbya martensiana Menegh. and pennate diatoms. Contrastingly, B. cf. algens was not found in Lakes Bonney, Hoare, Chad and Fryxell located in adjacent Taylor Valley, nor was it found in any ice-free littoral regions of the lakes of Taylor and Wright Valleys investigated during the 1980-81 austral summer. Bryum algens is the most widespread bryophyte south of 56°S in Antarctica. Its wide range of morphological forms has caused many problems in its taxonomy. Based upon examinations by one of us (R. I. L. S.), it is probable that B. korotkevicziae Sav.-Lyub. & Z. Smirn. and its variety hollebachii Sav.-Lyub. & Z. Smirn. and an unidentified aquatic Bryum sp. from Ablation Valley, Antarctica may be ecotypes of B. algens. The findings of B. cf. algens in Lake Vanda is the southernmost known occurrence of a moss from a perennially liquid deep water (>0.5 m) habitat.