According to the Institute of Oceanography in Nha Trang and Hai Phong, the sea surrounding the island have the wealth and the rich density of most species in Vietnam, many coral reefs are highly original nature, the survey recent marine life experts leading the majors always find a new species in the world and Vietnam.

     Marine biota has 1,493 species of statistics including: mangrove vegetation (forest Mangro) 23 species, Seaweed (Algae) 127 species, Seaweed (Seagrass) 11 species of phytoplankton (Phytoplankton) 157 species, zooplankton (zooplankton) 115 species, coral (coral), 342 species of mollusks (Mollusa) 187 species of coral reef fish (coral reef fishes) 202 species, crustaceans (Crustacea) 116 species, Da gai (Echiodermarta) 75 species, polychaete worms (Polycheta) 130 species, mammals and 8 species of marine reptiles.

     The research results have been recorded in waters up to 44 species of Con Dao is extremely rare genetic resources of Vietnam's sea and was included in the Red Book. These include: 02 species of seaweed, 02 species of mangrove plants, 03 species of coral, 12 species of molluscs, 01 crustaceans, 04 species of echinoderms, 07 species of fish, 07 reptiles, 05 birds and 01 species letter.

     Con Dao Sea has 3 main ecosystems: mangrove ecosystem covers an area of ​​18 hectares, seagrass ecosystems, covering about 200 hectares, the ecosystem of coral property covers approximately 1,000 hectares.

       + Coral ecosystem: the coral ecosystem is well developed in the area surrounding the Con Dao National Park, with 342 species, 61 varieties, 17 families. We can say the species composition of coral fauna Con Dao rich and varied in type first, second Vietnam. The dominant coral is Acropora, Porites, Pachyseris, Montipora, Panova, coral reef ecosystems contain high diversity of fish and other aquatic species; Spawning habitat, larval rearing, feeding of many marine species of marine Southeast region of Vietnam and Southeast Asia region. Coral reefs are also important in the regulation and balance the oxygen content in sea water and coastal protection Con Dao

       + Seagrass Ecosystems: A survey study sea surrounding the island has 11 species of seagrasses occupy 84.61% of the total number of known species present in Vietnam (13 species), more than 04 species of Singapore and more Brunei 06 species. The existence and growth of seagrass ecosystems have an important role as the main food source of the Dugong Dugon a rare species of mammals in the sea. At sea Con Dao with 8-12 individual Dugon Dugong, sea mammals this is the largest herbivorous exist and are particularly interested in the world, now only found in Con Dao and Phu Quoc.

      + Mangrove ecosystems: mangrove plant species in Con Dao has been identified as 23 species, dominant species that was changed (Rhizophora apiculata), Parrot though (Bruguiera gymnorrhiza), green mangrove (Rhizophora mucronata ).

     Also waters island also has reptiles and marine mammals:

       - Animal Beach: Coastal Con Dao animals usually appear 3: Delphin long snout (stenella longirostris), blue whale (Balaenoptera musculus) and Dugon dugon (it’s mean seacow). This is the third species of marine mammals protection concern, especially with animals dugon Dugong has long existed in Con Dao, but until 1995 the newly discovered. Currently Dugong object of interest is protected on a global scale.

       - Marine Reptiles: including sea turtles and sea snakes. Sea turtles: 2 species with large numbers living and to lay every year in Con Dao National Park: Chelonia mydas (green sea turtle) and Ertmochelys imbricata (hawksbill). Con Dao is also sea habitats of species foraging leatherbacks (Dermochelys coriacea), loggerhead (Lepidochelys olivacea). With 14 sea turtles spawning, Con Dao annual nesting numbers about 300 turtles mother, this is the turtle populations are evaluated accounting for 70-80% of sea turtle nesting / year in the territorial waters of Vietnam Male.