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
Coral reef complex and varied marine habitats that support a wide range of other organisms. Fringing reefs just below low tide level have a mutually beneficial relationship with mangrove forests at high tide level and sea grass meadows in between: the reefs protect the mangroves and seagrass from strong currents and waves that would damage them or erode the sediments in which they are rooted, while the mangroves and sea grass protect the coral from large influxes of silt, fresh water and pollutants. This level of variety in the environment benefits many coral reef animals, which, for example, may feed in the