Marine geoheritage is an important but still underdeveloped concept. Field investigations in the Abrau area (Krasnodar Region, southwestern Russia) and subsequent interpretations allow for the characterization of its geoheritage. Two geosites, namely Abrau and Limanchik, are delineated and assessed semi-qualitatively. Their high heritage value, complexity, and appropriate “technical” properties are appraised. The Abrau geosite features Abrau Lake with its enigmatic origin and the outcrops of deformed Upper Cretaceous carbonate flysch deposits. The Limanchik geosite represents an outstanding example of coastal abrasion, Paleocene siliciclastic flysch with trace fossils, and a coastal lagoon separated from the sea by a bar. The heritage aspects of the study areas are related to the development of the Late Cretaceous, Paleocene, and Pliocene seas, as well as to the active dynamics of the Black Sea coastal zone. The duality of marine geoheritage is linked to its relation to both ancient and modern marine environments.