Apo Reef sits roughly 33 kilometres off the western coast of Mindoro in the Silla Strait, and getting there is half the adventure — a two-hour banka ride from Sablayan that leaves you genuinely in the middle of nowhere.
This is the second largest contiguous coral reef system in the world, and unlike a lot of Philippine diving, the sheer distance from the mainland has protected it from the worst of the anchor damage and blast fishing that plagued closer sites. Reef health here is genuinely good by modern standards, though the 2010 bleaching event left visible scars on the shallower table corals, particularly on the eastern lagoon side.
Diving runs from around 5 metres on the reef flat to wall drop-offs that plunge well past 40 metres, so your certification level shapes your experience considerably. Visibility on a settled day sits between 20 and 30 metres, sometimes more.
The currents at the two main dive sites — Apo Reef North and Apo Island, not to be confused with the more famous Apo Island near Dumaguete — can run strong and unpredictable, which concentrates the big pelagic action.
Hammerheads move through in genuine numbers during the right conditions, manta rays cruise the channel, and whale sharks are reliable enough that operators flag sightings routinely rather than treating them as exceptional.
Most divers come on liveaboards departing Puerto Galera or Coron, which gives you three to four days on-site and the flexibility to dive at first light. Day boats from Sablayan exist but the crossing burns half your bottom time. A handful of small operators in Sablayan run basic kit hire and guides, though liveaboard vessels carry better equipment overall.
Open Water certified divers can access the shallower sections, but Advanced certification opens the walls and the pelagic action; plan for October through May when the Silla Strait calms down.