Apo Reef two lagoon systems, the north and south lagoons which are bounded by narrow reef platforms. It is a almost triangular northern and southern atoll-like reefs separated by a deep channel that is open to the west. The channel runs east to west from deep with a fine white sand bottom, numerous mounds and patches of branching corals under the deep blue water. The north lagoon is an enclosed triangular coral reef platform partly exposed during low tide. It is relatively shallow with depths of about . While the south lagoon is an inverted triangular coral platform enclosed on two sides
Réunion's coral reef for coral at Réunion is between 23 °C and 28 °C. Increased surface water temperature related to global warming can contribute to disease and bleaching of coral reefs, as is apparent on Réunion. Natural cyclones and anthropogenic disturbances such as urban development of catchment areas affect the reefs of Réunion. These ecological disturbances have led to an increase in coral reef nutrient levels via submarine groundwater discharge. Increased nutrient levels have resulted in the modification of flora and fauna in the benthic zone. The coral reef is a natural barrier that protects the coast from typhoons. The least vulnerable sectors