The material highlights the role of sargassum (Mo Seaweed) in conservation of marine biodiversity and climate changes mitigation, alarming the current destructive harvesting of sargassum in Nha Trang Bay and presenting a model of sustainable harvesting in order to protect marine resources. It has been developed under the project on "Developing sustainable livelihood based on Mo seaweed for fishermen living in the bank of Nha Trang bay to strengthen biodiversity conservation of the buffer zone of marine protected area of Nha Trang bay, Khanh Hoa province".