Abstract: Seagrasses are underwater flowering plants widely distributed in shallow seas often forming vast seagrass based ecosystems. Seagrass ecosystems are one of the most productive aquatic ecosystems in the world and a globally significant carbon store due to the unique features of seagrass which allow efficient photosynthesis underwater. Seagrass ecosystems provide a range of important ecological service functions and they act as biological sentinels used to assess the health of coastal ecosystems. Recently, rapidly decreases in the number of individual seagrass species and the number of seagrass meadows caused by the multiple stressors including natural factors and human effects had led to a situation where 14% of all seagrass species are at risk of extinction and about one-third seagrass meadows have disappeared worldwide. In response to this decline, there has been a significant increase in the number of marine protected areas during the last decade, including seagrass monitoring and restoration projects which aim to prevent the extinction of individual seagrass species and prevent the large scale loss of seagrass meadows throughout the world. Current restoration projects involve habitat improvement through reduction in eutrophication or alteration of hydrology and the use of artificial transplantations which can be an effective method of restoration. Seagrass monitoring and restoration projects have achieved some positive preliminary results and provide useful guidelines for seagrass restoration. However there are challenges including limited theoretical approaches, appropriate technology, and uncertainty of outcome from seagrass transplantation and restoration projects and cost. This paper reviews the research on seagrasses and seagrass ecosystems globally, clarifies their importance to the biosphere and the risks to their survival to raise the awareness of the public, government and international agencies of the need to protect seagrass ecosystems.