At 35 sq km, Apo Reef Natural Park (not to be confused with Apo Island off the south coast of Negros) is the largest atoll-type reef in the Philippines. Its crystal-clear waters abound with life, including 285 species of fish and 197 species of coral. It’s a wonderland for divers and snorkellers, with sightings of white-tip and black-tip sharks, reef sharks, wrasses, jacks and tuna all common.

You also stand a chance of seeing trophy creatures such as hammerhead sharks, whale sharks and manta rays out here. The reef's three islands play host to a variety of turtle and bird species, including the endangered, large-chicken-sized Nicobar pigeon.

Your average bangka makes the trip out to Apo Reef in about two hours from Sablayan in flat seas (a bit less from North Pandan Island, and a bit more from Calintaan). Liveaboard trips from Anilao, Puerto Galera and especially Coron also make it out here.

The best time to make the trip to Apo Reef is when the seas are flattest, during April, May, October and November. The journey is very rough during the windy December–March period. At the height of the southwest monsoon (July–September) it's often impossible to travel out to the reef and some operators shut down – be sure to call ahead.

At the time of research five operators were doing mostly overnight doing dive and snorkelling trips to Apo Reef: Pandan Island Resort, Gustav's Place, Sablayan Adventure Camp and Pentagon Diving in Sablayan; and Apo Reef Club in Calintaan.

Individuals or couples looking to split costs with other divers are advised to contact the Ecotourism Office in Sablayan, which can sometimes set you up with a group through one of the four Sablayan-based operators.

The Ecotourism Office also runs day or overnight snorkelling trips to Apo Reef. These cost P8000 per group for the boat (up to 15 people, two hours each way); plus the environmental fee; P1000 per day for a guide; and P300 for full snorkelling equipment (including fins). Bring your own lunch, water and snacks. Overnight trips involve sleeping in hammocks or on the floor of the open-air park ranger station on Apo Island, or on boats.