Apo Reef — Landseed

Depth · 0 to 1,194 m

Reef flat0–5 m

Reef slope5–30

Mesophotic30–150

Shelf break150–200

Strait slope200–900

Strait floor900–1,194 m

Boundary

Park boundarygazetted 1996

Depth bands are ecological, not evenly spaced — they mark the reef-building limit, the mesophotic floor and the shelf break. Vertical scale is non-linear: the top 40 m is shown at full scale and everything below is compressed, or the drop into the strait would flatten the reef to a sheet. Seafloor provenance: 55% of this frame comes from GMRT's high-resolution sounding compilation; the rest is interpolated from a coarser background grid and is measurably smoother. The closer Reef & Lagoons frame is 18% surveyed, so fine seafloor structure there is the model, not a survey. Depths are relative to approximately mean sea level with no tidal reduction, so the waterline on the drying reef flats is datum-dependent. No maritime-zone lines are drawn: the whole frame lies inside the Philippines' archipelagic baselines (RA 9522), so no baseline, territorial-sea or EEZ limit crosses it — the only boundary in frame is the park itself. No habitat layer is drawn: no licensed benthic habitat map reaches this reef (NOAA NCCOS, EUSeaMap and SGH all end elsewhere), and this map states that absence rather than filling it from a restricted database.

Live · reef condition

Heat stress—

Sea surface temp—

vs. normal for here—

Bleaching alert—

Surface current—

NOAA Coral Reef Watch

Heat stress is in degree heating weeks — accumulated stress over 12 weeks, not a temperature: 4 °C-weeks is where significant bleaching becomes likely, 8 where mortality does. Current is the ~25 km geostrophic field from altimetry — the regional set. It does not resolve tidal flow over the reef, which is the flow a diver feels.

Apo Reef Natural Park

The largest atoll-like reef in the Philippines, standing alone in the Mindoro Strait 30 km west of Sablayan — a 26 km reef platform whose three low islands are all that shows above water, protected whole since 1996 and closed to fishing in full since 2007.

Natural park

15,792 ha gazetted, Proc. 868 (1996)

Buffer zone

11,677 ha surrounding waters

No-take

whole reef since September 2007

Deepest in frame

1,194 m measured on this map's grid

Land

25.58 ha three islands

Proclamation No. 868 (6 September 1996) declared the Natural Park and its buffer; RA 11038 (2018) legislated it. Managed by a Protected Area Management Board under DENR, with a ranger station on Apo Island.

The boundary drawn here is the proclamation's own quadrilateral. The OpenStreetMap polygon this map renders matches all four corner coordinates in Proclamation 868 exactly, and its area computes to 15,844 ha against the proclamation's approximate 15,792 ha (+0.3%).

Fishing was banned across the whole reef in September 2007, converting the park to a no-take marine reserve — a designation, not a measured compliance rate; this map asserts only the first.

ASEAN Heritage Park (2024, the 61st) and on the UNESCO World Heritage tentative list since 2006.

The April 2014 site assessment recorded 190 reef fish species and 28 hard-coral genera across its 15 monitoring stations, with whitetip reef sharks the largest share of fish biomass — survey measurements, not totals.

No maritime-zone lines are drawn. The frame lies wholly inside the Philippines' archipelagic baselines (RA 9522, deposited with the UN), so no baseline, 12 nm or EEZ limit crosses it. The only line here is the park.

No habitat layer is drawn. No licensed benthic habitat map covers this reef: NOAA NCCOS (CC0) ends at US-affiliated Pacific waters, Europe's EUSeaMap at the Caribbean, and the one global reef atlas restricts commercial use. The absence is stated rather than filled.

Boundary: OpenStreetMap way/181365709 (ODbL), verified against the four corner coordinates of Presidential Proclamation No. 868, s. 1996 (0 m offset at every corner). Coastline: OpenStreetMap (ODbL), three closed island rings whose assembled area (0.267 km²) checks against the published 25.58 ha of island land. Bathymetry: GMRT synthesis (MGDS/Lamont-Doherty) at ~59 m, 55% of this frame from its high-resolution sounding compilation; land elevation composited from AWS Terrain Tiles (SRTM), because GMRT's land component invented a 51 m summit on islands that rise only a few metres. Imagery: cloud-free median of 14 Sentinel-2 L2A scenes, 2023–2025. Heat stress: NOAA Coral Reef Watch, 5 km. Figures from the MBCFI Rapid Site Assessment (April 2014) are survey measurements scoped to that survey.

Bathymetry: GMRT (Ryan et al. 2009) · Land elevation: AWS Terrain Tiles · Imagery: contains modified Copernicus Sentinel data (2023–2025) · Boundary & coastlines: OpenStreetMap (ODbL); park boundary verified against Presidential Proclamation No. 868 (1996) · Heat stress: NOAA Coral Reef Watch · Species silhouettes: PhyloPic (CC0, credited in ATTRIBUTION.md) · Globe texture: NASA · An independent visualization by Landseed PBC. Not affiliated with, endorsed by, or produced for any agency or organisation named here; credits identify data provenance and imply no endorsement.