Red tide is natural spectacle caused by the increasing number of single cell algae in the sea. Single cell algae that caused the Red tides are a dinoflagellate group. For example, Ceratium Gymnodinium and Protoperidinium. Population of single-cell algae that is much. Makes the sea is red. Which the color of the water can be changed into other colors, depending on the type of phytoplankton plants such as brown, green or yellow. Some red tides are associated with the production of natural toxins that can cause many harmful effects. In foreign countries, this happens many times, recently at Bondi Beach Australia