Seventy seamounts 50 to 100 km off South East Cape, southern Tasmania, rise from depths of 1000- 2000 m on the Australian continental slope. Sampling of the slopes of 14 seamounts was undertaken in 1997 by the Australian Commonwealth Scientific & Industrial Research Organisation (CSIRO). The collection yielded 14 species of hydroids, six of which are new, including two species of a new genus. Only Halecium fragile Hodgson, 1950, and Tripoma arboreum Hirohito, 1995, have previously been recorded from Tasmania. Other species are known from deep water off New Zealand, Japan and the south-western Atlantic.