This paper reports on the marine biodiversity and ethnobiodiversity of Bellona, a small island in Solomon Islands inhabited by Polynesians who have, for centuries, depended on biodiversity for their own sustainability. The Bellonese have names for at least 8 whales and dolphins, 7 reptiles, over 500 finfish, 191 molluscs, 48 crustaceans, 29 echinoderms and a range of corals, other invertebrates and marine plants, most of which have commercial, subsistence or cultural value. If conserved, this inheritance will continue to provide a foundation for continuing sustainability in a rapidly globalizing world. The paper highlights the importance of the preservation, and application to development, of ethnobiodiversity for food and subsistence security, and contingent issues of conservation and sustainability in small island developing states. As the current extinction crisis escalates globally, the rate of attrition of the intangible indigenous knowledge that has coevolved with this threatened biodiversity is probably far greater. In itself, the recording of information on biodiversity and related sustainable livelihoods is not sufficient to ensure sustainability. There is a vital need to integrate this into the formal education system and applied scientific activities at all levels to achieve the right balance between agriculture, wild harvest and trade, upon which sustainability and subsistence affluence still depend.