Apo Reef

The reef system of Apo Reef in Occidental Mindoro.

Apo Reef is a roughly triangular coral atoll formation approximately 26 kilometres (16 mi) from the north to the south tip, and 20 kilometres (12 mi) from east to west. It is separated by two lagoon systems, the north and south lagoons which are bounded by narrow reef platforms. It is 34 square kilometres (13 sq mi) of 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 1.8 to 30 metres (5 ft 11 in to 98 ft 5 in) 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 2–10 metres (6 ft 7 in – 32 ft 10 in). While the south lagoon is an inverted triangular coral platform enclosed on two sides and is about 30 metres (98 ft) in depth. Likewise, reef limestone and coralline sand on the east and southeastern sides dominantly underlie the area.

The main geographical feature of Apo Reef is submerged, but three islands mark it on the surface: the Apo Island, Apo Menor (locally known as Binangaan) and Cayos del Bajo ("Keys of the bank", locally known as Tinangkapan).[5] The islands are uninhabited. Since the declaration of "no-take-zone" policy at Apo Reef Natural Park in 2007, only protected area personnel and members of the Task Force MARLEN (Marine and Apo Reef Law Enforcement for Nature), who are tasked to implement protection and conservation work at the park, stay in the protected area on weekly shifts.

The largest island in the Apo Reef has a lighthouse, white beach, lagoon, mangroves, and karstic rock formations.

The largest is Apo Island at 22 hectares (54 acres) with mangroves and beach vegetation. The reef surrounding the island extends to 0.80 kilometres (1⁄2 mi) in places. Outside the lagoonal mangroves in the eastern and southern sides of Apo Island, the soil is sandy-to-sandy loam that has less silt and clay particles, while the lagoonal mangroves have a sandy loam to clay loam soil, underlain by decomposed plant residues or coarse materials.[5]

Apo Island is separated from Apo Reef by a narrow, deep channel. The island is about 23 nautical miles (43 km; 26 mi) from Mindoro and about 20 nautical miles (37 km; 23 mi) from Nanga and Tara Islands, the nearest of the islands off Busuanga Island on the western side of the Mindoro Strait. The Apo Reef Light, situated on the northeast part of the island, warns ship about the location of this navigational hazard.[3] The island is situated at a two and a half hour navigation 240° from Sablayan by pump boat (banka).

The island houses a permanent ranger base which monitors the national park. An administrative desk collects the environmental fees. It is possible to stay overnight in tents subject to certain conditions. Very limited facilities are available onshore to protect the island's fragile ecosystem.

The Apo Menor Island is the second largest island in the Apo Reef and is primarily made up of rocks.

Apo Menor is located near the western end of Apo Reef, about 2.4 kilometres (1.5 mi) east of Apo Island.[3] It is a rocky limestone island with relatively little vegetation.[5]

Cayos del Bajo are flat coralline rock formations with no vegetation on the northern lagoon near the eastern edge of the reef. At low tide, many small rocks are dry on the reef, particularly along its north side.[3][5]