Abstract In this study, marine algae and sea grasses in the upper infralittoral zone of the Black Sea coast of Giresun (Black Sea, Turkey) have been examined. Totally 193 taxa have been determined. 18 of them belong to blue-green bacteria (Cyanobacteria), 109 to red algae (Rhodophyta), 33 to brown algae (Ochrophyta), 30 to green algae (Chlorophyta) and 3 to sea grasses (Magnoliophyta). Erythrotrichia investiens, E. vexillaris, Lophosiphonia scopulorum and Spermothamnion repens var. flagelliferum are new records for Turkish shores of the Black Sea.