Haa Long Bay features ecosystems of a tropical ocean region, such as: salt water-flooded forests, coral reefs and tropical rain forests. H?a Long Bay is home to 163 species of coral, from 44 lines of descent and 12 families. Coral reefs are distributed everywhere usually at a depth of 4 to 6m. The coverage rate of coral reef is 30% on average. There are areas where it attains 70 to 80%, such as at Cong Do and B? Hung. The coral forests of Ha Long Bay are a wonderful sight, with many extraordinary shapes and diversified colors.
The reefs are residence to a great number of species. There are primarily 107 varieties of fishes, water plants, algae and transitory animals and plants. Also living in these flooded forests are a great many species of animals. These include migrating 37 species of birds, 81 species of sea-bottom animals and fish belonging to 55 families. Fishing is the lifeblood of most Vietnamese, and features prominently in all their dishes.
In particular, bottom-feeders account for 61% of the total species in the whole tidal region, with many species like arcae, meretrixes and all kinds of crustaceans being of great economic value.
The tropical rain forest ecosystem also features a rich quantity of species: dinh, huong, sen, tau trees. This is the residence of various rare and precious creatures like deer, weasels, squirrels and in particular, white-tabby and red-haired monkeys