Macroalgae in Kongsfjorden were surveyed by divers down to 30 m depth at Hansneset, Blomstrand (78° 39’N, 11°57’E). In total, 62 species were identified, 16 Chlorophyta, 25 Phaeophyceae and 21 Rhodophyta. The majority of species (53.5%) belonged to the Arctic cold-temperate group, followed by species distributed from the Arctic to the warm-temperate region (25.9%). Four endemic Arctic species (Laminaria solidungula, Acrosiphonia flagellata, A. incurva, Urospora elongata) were found. Two species (Lithosiphon filiformis, Mikrosyphar polysiphoniae) were new for Svalbard. Chlorophyta, Phaeophyceae and Rhodophyta extended from the eulittoral zone down to 11, 21 and >30 m depths, with maximum biomasses at 1- 5 m, 5- 10 m and 5- 30 m depth, respectively. Annual and pseudoperennial species had highest biomasses in the upper 5 m, while perennials were distributed deeper. The highest biomass (8600 g m-2) at 5 m depth included mainly Laminaria digitata, Saccorhiza dermatodea, Alaria esculenta and Saccharina latissima. The biogeographic composition of macroalgae at Hansneset was relatively similar to that of Northeast Greenland, but different from that of Northern Norway, which is characterised by a higher proportion of temperate species. Climate warming and ship traffic may extend some of the distribution ranges of macroalgae from mainland Norway to Svalbard.