Abstract In this research, marine algae and seagrasses in the upper infralittoral zone of the Black Sea, coast of Kastamonu, was investigated. A total of 259 algae and 3 seagrasses taxa were determined. These are the blue-green bacteria (22 taxa), red algae (133 taxa), the brown algae (56 taxa), the green algae (48 taxa) and the flowering plants (3 taxa). Eupogodon planus, Spermothamnion repens (Rhodophyceae), Planophila microcystis and Stromatella monostromatica (Fucophyceae) are new records for Black Sea and Turkish black sea shores.