In Republican China, controversies over antiquities and fossils management during Western expeditions in China prompted new laws and policy regulating foreign biological expeditions in China’s interiors. Luo Guihuan has examined the restrictions introduced by Academia Sinica to limit Westerners’ collecting endeavors of Chinese fauna and flora while Fan Fa-Ti has analyzed the ways in which natural history was incorporated into the nation’s body in Republican China. However, most of these “restrictions” triggered by nationalistic sentiments were targeted on terrestrial exploration, mostly in Northwestern China (such as the Central Asiatic Expeditions of the American Museum of Natural History), where the spotlight was placed on fossils or endangered species such as pandas. Historians of science have suggested that animals and plants are not just objects of naturalists’ interests but also subjects of nationalists’ sentiments in the age of Western imperialism. But most of the available evidence came from terrestrial flora and fauna, without much discussion of the connection between nationalism and marine flora and fauna. Drawing from the evidence of the marine biological surveys in Republican China, this paper explores the relationship between marine biological expeditions and nationalism, and suggests that while coastal biological organisms were imbued with local meanings, marine biological research in Republican China was essentially a transnational enterprise and not restricted the same way as land-based investigations.