In 2021 and 2025, transect surveys of coastal biotopes were conducted in the Onezhskoye Pomorye National Park. The transect length totaled over 100 km. The diversity of plant communities was identified for the surveyed areas, and a hierarchical scheme of biotopes (habitats) was produced: 3 classes, 11 subclasses of level 1 (types of geomorphological elements: shallow waters, marshes, sandy beaches, boulder-pebble beaches, swampy lagoons and bays, modern marine sand and sand-boulder terraces, steep slopes of marine terraces, dunes, river estuaries, river floodplains, late Holocene marine terraces), 58 subclasses of level 4 (types of plant communities). Three communities are classified as extremely rare, including species listed in the Red Data Book of the Russian Federation (Rhodiola rosea) and in the Red Data Book of the Arkhangelsk Region (Blysmus rufus and Primila farinosa). Nineteen biotope types were recognized as deserving further study and special protection. The biotope mapping done for two core areas demonstrates a highly mosaic coastal vegetation pattern.