Coral Reef Diagnostics

Philippines - Visayas

NOAA Coral Reef Watch

Regional summary of 7 dive sites. Figures are averages across the sites that report them (n = sites with a value); each site's own page has its individual values. Part of the Philippines overview.

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05
Sites
7
each linked below
Hard coral cover (regional mean)
—
n = 0 of 7 sites
Water temp. during surveys (regional mean)
—
n = 0 of 7 sites
Coral Health Index (regional mean)
not yet scored
n = 0 of 7 sites
Most recent water temperature record
16 Sep 2026 · Eastern Philippines
Most recent heat stress record
16 Sep 2026 · below alert level
Mean annual max degree heating weeks (DHW), last 5 years
2021–2025 · Eastern Philippines
Highest annual heat stress
in 2024 · Eastern Philippines
Severe heat-stress years
1985–2025 · 2 in the last 10 years
Heat-stress figures: NOAA Coral Reef Watch — Eastern Philippines 5-km virtual station. Each pill links its source record and carries the values behind it.
Regional summary

Anderson's 2013 dives around Cebu, Bohol, Negros, and Boracay are known from his logs: mostly walls with repeatedly outstanding hard coral, including the trip's best coral dive at Moalboal. Pressures were few but specific, including typhoon-toppled table corals and an overfished Sipalay fish assemblage.

Heat stress

04812Week of 2023-05-07: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 30.05°CWeek of 2023-05-14: DHW 1.3°C-weeks (below the bleaching alert threshold); SST 30.34°CWeek of 2023-05-21: DHW 2.6°C-weeks (below the bleaching alert threshold); SST 30.57°CWeek of 2023-05-28: DHW 2.6°C-weeks (below the bleaching alert threshold); SST 29.78°CWeek of 2023-06-04: DHW 2.6°C-weeks (below the bleaching alert threshold); SST 30.09°CWeek of 2023-06-11: DHW 2.7°C-weeks (below the bleaching alert threshold); SST 30.24°CWeek of 2023-06-18: DHW 3.7°C-weeks (below the bleaching alert threshold); SST 30.47°CWeek of 2023-06-25: DHW 4.4°C-weeks (Alert Level 1: significant bleaching likely); SST 30.53°CWeek of 2023-07-02: DHW 5.2°C-weeks (Alert Level 1: significant bleaching likely); SST 30.17°CWeek of 2023-07-09: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 30.00°CWeek of 2023-07-16: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 29.55°CWeek of 2023-07-23: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 29.24°CWeek of 2023-07-30: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 29.47°CWeek of 2023-08-06: DHW 5.2°C-weeks (Alert Level 1: significant bleaching likely); SST 29.84°CWeek of 2023-08-13: DHW 4.2°C-weeks (Alert Level 1: significant bleaching likely); SST 29.72°CWeek of 2023-08-20: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.86°CWeek of 2023-08-27: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.48°CWeek of 2023-09-03: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.50°CWeek of 2023-09-10: DHW 3.0°C-weeks (below the bleaching alert threshold); SST 30.25°CWeek of 2023-09-17: DHW 2.2°C-weeks (below the bleaching alert threshold); SST 30.37°CWeek of 2023-09-24: DHW 1.9°C-weeks (below the bleaching alert threshold); SST 29.78°CWeek of 2023-10-01: DHW 1.1°C-weeks (below the bleaching alert threshold); SST 29.76°CWeek of 2023-10-08: DHW 0.8°C-weeks (below the bleaching alert threshold); SST 29.89°CWeek of 2023-10-15: DHW 1.6°C-weeks (below the bleaching alert threshold); SST 30.26°CWeek of 2023-10-22: DHW 2.8°C-weeks (below the bleaching alert threshold); SST 30.24°CWeek of 2023-10-29: DHW 3.8°C-weeks (below the bleaching alert threshold); SST 30.32°CWeek of 2023-11-05: DHW 4.1°C-weeks (Alert Level 1: significant bleaching likely); SST 30.08°CWeek of 2023-11-12: DHW 4.1°C-weeks (Alert Level 1: significant bleaching likely); SST 29.80°CWeek of 2023-11-19: DHW 4.1°C-weeks (Alert Level 1: significant bleaching likely); SST 29.37°CWeek of 2023-11-26: DHW 4.1°C-weeks (Alert Level 1: significant bleaching likely); SST 29.08°CWeek of 2023-12-03: DHW 4.1°C-weeks (Alert Level 1: significant bleaching likely); SST 29.04°CWeek of 2023-12-10: DHW 4.0°C-weeks (below the bleaching alert threshold); SST 28.90°CWeek of 2023-12-17: DHW 3.3°C-weeks (below the bleaching alert threshold); SST 28.84°CWeek of 2023-12-24: DHW 3.3°C-weeks (below the bleaching alert threshold); SST 28.65°CWeek of 2023-12-31: DHW 3.3°C-weeks (below the bleaching alert threshold); SST 28.92°CWeek of 2024-01-07: DHW 3.2°C-weeks (below the bleaching alert threshold); SST 28.77°CWeek of 2024-01-14: DHW 2.3°C-weeks (below the bleaching alert threshold); SST 28.14°CWeek of 2024-01-21: DHW 1.2°C-weeks (below the bleaching alert threshold); SST 28.16°CWeek of 2024-01-28: DHW 0.2°C-weeks (below the bleaching alert threshold); SST 27.69°CWeek of 2024-05-05: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 30.18°CWeek of 2024-05-12: DHW 1.6°C-weeks (below the bleaching alert threshold); SST 30.63°CWeek of 2024-05-19: DHW 3.0°C-weeks (below the bleaching alert threshold); SST 30.83°CWeek of 2024-05-26: DHW 4.3°C-weeks (Alert Level 1: significant bleaching likely); SST 30.68°CWeek of 2024-06-02: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 30.81°CWeek of 2024-06-09: DHW 7.1°C-weeks (Alert Level 1: significant bleaching likely); SST 30.90°CWeek of 2024-06-16: DHW 8.6°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.92°CWeek of 2024-06-23: DHW 9.9°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.71°CWeek of 2024-06-30: DHW 11.0°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.36°CWeek of 2024-07-07: DHW 11.5°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.17°CWeek of 2024-07-14: DHW 11.6°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.03°CWeek of 2024-07-21: DHW 11.6°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 29.63°CWeek of 2024-07-28: DHW 11.9°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.01°CWeek of 2024-08-04: DHW 11.4°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.14°CWeek of 2024-08-11: DHW 10.2°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.42°CWeek of 2024-08-18: DHW 10.1°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.75°CWeek of 2024-08-25: DHW 10.1°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.38°CWeek of 2024-09-01: DHW 9.6°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 29.89°CWeek of 2024-09-08: DHW 8.1°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.01°CWeek of 2024-09-15: DHW 6.9°C-weeks (Alert Level 1: significant bleaching likely); SST 29.58°CWeek of 2024-09-22: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 29.83°CWeek of 2024-09-29: DHW 4.5°C-weeks (Alert Level 1: significant bleaching likely); SST 29.72°CWeek of 2024-10-06: DHW 4.4°C-weeks (Alert Level 1: significant bleaching likely); SST 29.98°CWeek of 2024-10-13: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 30.37°CWeek of 2024-10-20: DHW 6.0°C-weeks (Alert Level 1: significant bleaching likely); SST 29.92°CWeek of 2024-10-27: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 29.48°CWeek of 2024-11-03: DHW 5.7°C-weeks (Alert Level 1: significant bleaching likely); SST 29.55°CWeek of 2024-11-10: DHW 4.6°C-weeks (Alert Level 1: significant bleaching likely); SST 29.90°CWeek of 2024-11-17: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.73°CWeek of 2024-11-24: DHW 2.2°C-weeks (below the bleaching alert threshold); SST 29.27°CWeek of 2024-12-01: DHW 2.2°C-weeks (below the bleaching alert threshold); SST 29.35°CWeek of 2024-12-08: DHW 1.9°C-weeks (below the bleaching alert threshold); SST 29.24°CWeek of 2024-12-15: DHW 1.9°C-weeks (below the bleaching alert threshold); SST 28.88°CWeek of 2024-12-22: DHW 1.9°C-weeks (below the bleaching alert threshold); SST 28.57°CWeek of 2024-12-29: DHW 1.9°C-weeks (below the bleaching alert threshold); SST 28.61°CWeek of 2025-01-05: DHW 1.4°C-weeks (below the bleaching alert threshold); SST 28.75°CWeek of 2025-01-12: DHW 0.2°C-weeks (below the bleaching alert threshold); SST 28.60°CWeek of 2025-05-04: DHW 0.1°C-weeks (below the bleaching alert threshold); SST 29.95°CWeek of 2025-05-11: DHW 1.3°C-weeks (below the bleaching alert threshold); SST 30.48°CWeek of 2025-05-18: DHW 1.5°C-weeks (below the bleaching alert threshold); SST 30.32°CWeek of 2025-05-25: DHW 1.7°C-weeks (below the bleaching alert threshold); SST 30.23°CWeek of 2025-06-01: DHW 3.0°C-weeks (below the bleaching alert threshold); SST 30.54°CWeek of 2025-06-08: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.99°CWeek of 2025-06-15: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.88°CWeek of 2025-06-22: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.89°CWeek of 2025-06-29: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.79°CWeek of 2025-07-06: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.95°CWeek of 2025-07-13: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.67°CWeek of 2025-07-20: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.43°CWeek of 2025-07-27: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 29.62°CWeek of 2025-08-03: DHW 2.8°C-weeks (below the bleaching alert threshold); SST 29.98°CWeek of 2025-08-10: DHW 2.0°C-weeks (below the bleaching alert threshold); SST 29.82°CWeek of 2025-08-17: DHW 2.0°C-weeks (below the bleaching alert threshold); SST 29.78°CWeek of 2025-08-24: DHW 1.5°C-weeks (below the bleaching alert threshold); SST 29.61°CWeek of 2025-08-31: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.41°CWeek of 2025-09-07: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.47°CWeek of 2025-09-14: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.47°CWeek of 2025-09-21: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.50°CWeek of 2025-09-28: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.61°CWeek of 2025-10-05: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.62°CWeek of 2025-10-12: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.79°CWeek of 2025-10-19: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.70°CWeek of 2025-10-26: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 29.71°CWeek of 2025-11-02: DHW 0.1°C-weeks (below the bleaching alert threshold); SST 29.84°CWeek of 2026-05-10: DHW 0.3°C-weeks (below the bleaching alert threshold); SST 30.00°CWeek of 2026-05-17: DHW 1.5°C-weeks (below the bleaching alert threshold); SST 30.40°CWeek of 2026-05-24: DHW 2.7°C-weeks (below the bleaching alert threshold); SST 30.46°CWeek of 2026-05-31: DHW 3.1°C-weeks (below the bleaching alert threshold); SST 30.21°CWeek of 2026-06-07: DHW 4.7°C-weeks (Alert Level 1: significant bleaching likely); SST 30.93°CWeek of 2026-06-14: DHW 6.3°C-weeks (Alert Level 1: significant bleaching likely); SST 31.04°CWeek of 2026-06-21: DHW 7.0°C-weeks (Alert Level 1: significant bleaching likely); SST 30.45°CWeek of 2026-06-28: DHW 7.6°C-weeks (Alert Level 1: significant bleaching likely); SST 30.29°CWeek of 2026-07-05: DHW 8.4°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.65°CWeek of 2026-07-12: DHW 8.4°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.22°CWeek of 2026-07-19: DHW 8.7°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.24°CWeek of 2026-07-26: DHW 8.7°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 30.05°CWeek of 2026-08-02: DHW 8.7°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 29.79°CWeek of 2026-08-09: DHW 8.3°C-weeks (Alert Level 2+: severe bleaching and significant mortality likely); SST 29.63°CWeek of 2026-08-16: DHW 7.1°C-weeks (Alert Level 1: significant bleaching likely); SST 29.67°CWeek of 2026-08-23: DHW 5.9°C-weeks (Alert Level 1: significant bleaching likely); SST 29.96°CWeek of 2026-08-30: DHW 5.4°C-weeks (Alert Level 1: significant bleaching likely); SST 29.68°CWeek of 2026-09-06: DHW 3.8°C-weeks (below the bleaching alert threshold); SST 29.81°CWeek of 2026-09-13: DHW 2.3°C-weeks (below the bleaching alert threshold); SST 29.77°C26272829303132Bleaching threshold 30.4°C2023202420252026SST (°C)DHW (°C-weeks)
sea surface temperature (SST) (left axis)DHW under 2DHW 2–3DHW 3–5DHW 5–8DHW 8–10DHW over 10 (🔥 above 12)
Daily SST (line) and weekly maximum Degree Heating Weeks (bars), Jan 2023–Sep 2026, NOAA Coral Reef Watch 5-km Eastern Philippines virtual station. Dashed line: bleaching threshold (maximum monthly mean 29.4°C + 1°C). DHW ≥ 4: bleaching likely; ≥ 8: severe bleaching and mortality likely. A bar is drawn only where DHW exceeds zero, so a stretch with no bar is accumulated heat stress of zero, not missing data — the SST line runs the full period.

Long-term record: 3 years since 1985 reached 8 or more °C-weeks at NOAA’s Eastern Philippines station. Download the annual DHW data (CSV).

7 sites in this region — click a marker to open that site.

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Regional setting

Spalding et al. (2001) describe the Visayas as a close-set group of islands, among them Panay, Negros, Cebu, Bohol, Leyte, and Samar, arranged around the Visayan Sea, which exceeds 200 m in depth in places. Fringing reefs line much of the Visayan coast, broken by soft sediment near river mouths, and on some reefs live cover was above 50%. Fish diversity was high where reefs were protected or lightly fished, and the small reserves at Apo Island and Sumilon, off Negros and Cebu, are cited as globally recognized models of community-based management: tiny no-take zones, enforced for years, raised fish numbers, and sizes and lifted yields in surrounding waters, and from 1999 both islands collected fees from visiting dive boats. Against this, Toledo City on Cebu was discharging an estimated 100,000 tons of mine tailings a day, with heavy losses of fish and coral along 7 km of coast. Their protected-area list includes the Apo Island Protected Landscape/Seascape (6.91 km², 1996), the Panglao Island-Balicasag reserve (1978), and Moalboal/Pescador. Nationally, they estimate 25,060 km² of reef, with 421 coral species recorded and 577 estimated.

By 2004, according to Wilkinson (2006), reef decline was continuing in the Philippines, driven by overfishing and destructive fishing, pollution and sediment running off the land, and reclamation. The same review judged only 10-20% of Southeast Asia's more than 630 marine protected areas to be effectively managed, which makes enforced reserves like Apo and Sumilon the exception. Souter et al. (2021) estimate that hard coral cover across the East Asian Seas dropped to 35% by 2012 after the 2010 mass bleaching and to 33.9% in 2017 after the 2016 event, before recovering to about 36.8% in 2019, and they flag marine plastic litter as an emerging threat in a region that may generate up to half of the world's supply.

Overview

The seven Visayas pins cover recreational dives made in February 2013 around Moalboal and Pescador Island off western Cebu, Mactan Island beside Cebu City, Alona Beach on Panglao and Balicasag Island off Bohol, Apo Island off Negros, Punta Ballo at Sipalay in Negros Occidental, and Boracay. The underwater record here comes from Anderson's dive logs rather than photographs, since the surviving frames from these trips are topside.

The logs describe walls as the common setting: a wall at about 10 m at Sambaguita, a 32 m wall at Pescador Island, the deep Sanctuary wall on Balicasag, a wall with a cavern opening at about 25 m at Marigondon Cave on Mactan, and a deep wall through the Chapel dive at Apo. Sipalay offered a reef slope at Dante's Peak and pronounced spur-and-groove coral canyons at Habok Habok, and Boracay's Balinghai dive ran through a rubble canyon between two reef walls.

Hard coral was repeatedly the highlight. Talisay at Moalboal was the dive Anderson rated best of the trip for coral, close to continuous and genus-rich, with poritids, agaricids, acroporids, pocilloporids, fungids, and gonioporids logged. The Sambaguita shallows at 3-4 m were near-continuous branching Porites, Pescador had extensive Montipora in the shallows, and the Balicasag Sanctuary wall carried the most coral he had then seen on one dive, turning to mostly encrusting forms with depth. At Marigondon Cave the log calls the hard coral cover and diversity striking given how close the site is to Cebu City. The exit there was through a coral garden interspersed with seagrass.

Pressures in the logs are few but specific: tabular acroporids overturned at Arco Point by a strong typhoon about two months earlier, and a Sipalay fish assemblage that appeared severely overfished despite good coral structure. Sightings include turtles at several sites, a juvenile blue-ringed octopus on the Moalboal night dive, trevally and sardine schools off Mactan and Balicasag, and at Boracay abundant tabular acroporids, at least fifteen nudibranchs, and the largest cuttlefish and mantis shrimp he had then seen.

Highlights

Notable observations

Coral cover over time (pooled)

One point per year: the mean of every hard coral cover value available for this region that year — Anderson’s own dives and every independent survey station within 5 km of them. The vertical bar is the full range behind that mean. Different programs use different methods at different stations, so this is a regional summary, not a single comparable series. Years resting on fewer than three values are drawn as smaller points (1998, 1999, 2000, 2001, 2012, 2013, 2016, 2023). Non-CRD points are from Reef Check Foundation.
0%17%34%51%68%1998 bleaching1998201020231998: mean 61% of 1 value1999: mean 43% of 1 value2000: mean 35% of 1 value2001: mean 20% of 2 values (range 12–27%)2002: mean 29% of 7 values (range 17–42%)2003: mean 28% of 15 values (range 7.5–50%)2004: mean 18% of 10 values (range 5.6–37%)2005: mean 22% of 11 values (range 11–44%)2006: mean 17% of 19 values (range 2.8–56%)2007: mean 24% of 16 values (range 4.4–51%)2012: mean 32% of 1 value2013: mean 18% of 1 value2016: mean 50% of 1 value2017: mean 17% of 4 values (range 11–20%)2023: mean 14% of 1 value

Sites in this region

Nearby external survey stations

96 independent survey records within 5 km of a site in this region (deduplicated across sites).

Show all 96 records

Data are from Coral Reef Diagnostics and Reef Check Foundation.

© Coral Reef Diagnostics.

References