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 fish line speed, so coral reef fish have developed bodies which optimize their ability to dart and change direction. They outwit predators by dodging into fissures in the reef or playing hide and seek around coral heads. Many reef fish, such as butterflyfish and angelfishes, have evolved bodies which are deep and laterally compressed like a pancake. Their pelvic and pectoral fins are designed differently, so they act together with the flattened body to optimise manoeuvrability. Coral reef fishes exhibit a huge variety of dazzling and sometimes bizarre colours and patterns. This is in marked contrasts to open water fishes which