Out of 65 200-ml seawater samples collected over coral and algal growths in the Torres Strait region, 45 contained viable yeasts; the average viable cell count was 11.5. No yeasts were found in open channels of the Torres Strait, through which Coral Sea or Arafura Sea water flows; nor in water over sandy or rocky bottoms. of a total of 12 representative isolates, 6 were unidentified “black yeasts” and 6 belonged to the following species:Candida reukauffii, Pichia farinosa, Saccharomyces estuarii, C. marina nov. spec.,Torulopsis torresii nov. spec., andT. maris nov. spec. Descriptions and Latin diagnoses of the new species are given. The use of speciation studies as an approach to marine yeast ecology is discussed.