One Health, Planetary Health, and EcoHealth – there are myriad conceptual frameworks for expanding discussions to move beyond human, animal and plant health, to be inclusive for the health of ecosystems. At present, however, despite its crucial role in the survival of our world, the ocean receives insufficient consideration within these frameworks. Therefore, greater emphasis should be placed on what can be coined One Ocean Health. To this end, we relate the health of the ocean to currently dominant connotations of the concept of health and acknowledge the ocean’s nature as one gigantic, interconnected ecosystem; a common, irreplaceable ocean on which all living things depend, human and non-human, terrestrial and aquatic alike. Recognizing the interconnectedness of ocean and society, and drawing on concepts from medical theory, we advocate for a holistic, co-developed approach to ocean health that integrates not only scientific and policy perspectives but also acknowledges the cultural diversity in the ways in which people relate to the ocean and engage with it. To achieve this, objective and subjective perspectives of what constitutes “diseases” in marine ecosystems need to be considered, while also defining means and normative goals of a “healthy ocean” – always bearing in mind the fact that this is not an end in itself, but remains crucial for the preservation of the planet that we as humans need.