Coral Reef Diagnostics

Alor - Goa Wolang (Walang Cave)

Komodo Dragon Liveaboards — Naga Biru
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05
Photo: Anderson Mayfield/Coral Reef Diagnostics
Country
Survey date(s)
2026-07-30
Coordinates
-8.3583, 124.3684
Coral cover
7.7%
Claude computer vision (28 photos) · other methods below · median 5.4%
Observations
fishing gear
Heat stress
Most recent heat load record
26 Oct 2026 · No heat stress
5-year thermal stress load
5-year mean max. degree heating weeks (DHW)
2021–2025
NOAA Coral Reef Watch — East Nusa Tenggara virtual station
i 5-year mean max. DHW is the mean of the annual maximum DHWs over the five complete years named above, not conditions today.
More infoEast Nusa Tenggara (NOAA CRW virtual station) Alor and the Pantar Strait sit in a zone of exceptionally strong upwelling, which holds these reefs several degrees cooler than NOAA’s satellite-derived figures imply. Read the heat-stress numbers here as a regional-scale indication, not as this reef’s own temperature history.
Photographs
33
Site summary
Read this summary in:

An Alor dive in three parts: a shaded overhang crusted in magenta coralline algae and hung with orange soft corals, a cave whose torch-lit interior holds only sponges and a solitary cup coral, and a broad pavement of coralline-crusted rubble with scattered live coral heads. The short photo set makes this more a record of the cave than of the reef.

Max. depth dived
12.8 m
dive-log maximum
Water temp. during survey
24–25°C
Water-temperature range logged on the dive (24-25°C, the author's dive notes).
Bottom time
62 min
in at 15:21
Dive setting
Cave · Advanced

Three other CRD dive sites with their own pages within 5 km shown in orange — click a marker to open its page.

These are unedited originals; edited versions will replace them.

28 of the 33 photographs on this page are shown beside the text that discusses them under "Site description" below.

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Photo credit & attribution

Site description

Setting

Frame by frame this dive splits into three habitats. The cave: two frames show the entrance as a dark arch with a diver silhouetted in blue water, one looks back out at a bright triangular mouth (e.g., Image 16).

In the wide frames the water looks clear. A rugged cave entrance and adjoining rocky reef with chambers and swim-throughs. Live hard coral was patchy and discontinuous, and the short sequence makes this primarily a topographic record.

General benthic features

Outside the cave, a shaded overhang and boulder base is carpeted in crustose coralline algae in magenta, rose, and red, studded with red and orange encrusting sponges (e.g., Image 1, Image 6, Image 13).

Coral here is overwhelmingly foliose and laminar, not branching: overlapping pale-brown plates with upturned, pale-edged margins, small fleshy folded merulinid or lobophylliid polyps, squat leather corals, and bushy orange tree-like soft corals hanging from the roof with anthias beneath (e.g., Image 7, Image 9, Image 12, Image 21).

Four torch-lit interior frames hold no zooxanthellate coral at all — only white, yellow, and salmon encrusting sponges, spaghetti-like sponge processes, bryozoan or serpulid crusts, and one solitary cup coral with a ribbed brown wall and a ring of pale swollen polyp vesicles, shot three times (e.g., Image 10, Image 14, Image 19, Image 22).

The main habitat is an open low-relief pavement of coralline-crusted rubble, cobble, and dead framework — repeatedly the dominant substrate in the set (e.g., Image 4, Image 5, Image 15, Image 20, Image 25).

Live coral sits on it as isolated heads and patches: a tabulate Acropora beside a domed colony, a stout blue-gray branching colony with blunt tips, green-yellow digitate Acropora, meandroid brains, one large pale-green finely divided arborescent colony, feather stars, green turf, small gorgonians, a black long-spined urchin (e.g., Image 2, Image 18, Image 24, Image 28, Image 32).

Coral cover

Stressors

No bleaching, disease, or predation was evident — hard coral simply holds a minority of a mostly coralline-and-rubble surface (e.g., Image 29, Image 35).

Fishing gear: two woven-bamboo fish traps (bubu) with buoy lines lie on the rubble (e.g., Image 37), and a thick, fouled rope lies in loops across the rubble and sand (e.g., Image 15).

Fish and other fauna

Fish were anthias and Chromis swarms, blue damselfishes, a yellow Chaetodon, and orange soldierfish; two shallow frames climb a near-surface wall dense with orange cup-coral-like polyps (e.g., Image 11, Image 31, Image 36).

Comparisons with other data

We found no other surveys at this site as of 2026. If you would like to share yours, please email us.

Regional context, not a survey of this site: Razak et al. (2026) found no significant trend in hard coral cover around Alor (a decline of 0.6% per year at 23 sites, surveyed by point-intercept transect at about 8–10 m in 2014, 2017, 2021, and 2023 by Yayasan WWF Indonesia); this is a trend for that location, not this site’s cover. Cover at those sites fell by 3% between the 2014 and 2017 surveys, which bracket 75 days of NOAA Bleaching Alert Level 1 from December 2016 to February 2017.

CV model comparison

Mean 7.7%, median 5.4% across 28 photos.
More infoA few colony-focused photos raise the mean; the median is the typical photo. No computer-vision method yet estimates coral cover accurately on new images, so treat this as indicative rather than a measurement; it is revised as the methods improve.
Headline: Claude computer vision — a blind point count of this site's own photographs.
More infoDINOv3 and CoralSCOP were run on the same photos and are listed for comparison. No diver transect exists for this trip, so agreement between the rows is not accuracy, and no computer-vision method yet estimates coral cover accurately on new images; treat every row as indicative.
MethodHard coral cover (%)Photos (n) ± SE
In-house DINOv319.1n = 28 · SE 1.5
CoralSCOP unedited8.8n = 28 · SE 1.5
Claude7.7n = 28 · SE 1.7

The two computer-vision methods disagree by 10.3 pp (8.8–19.1%) and read 1.1–11.4 pp above Claude's blind point count (7.7%); the headline is Claude's blind point count because no transect or manual count exists here.

Data & links

All images from Coral Reef Diagnostics. Data are from Coral Reef Diagnostics.

© Coral Reef Diagnostics.

References

  1. Razak TB, Alisa CAG, Abrar M, Ardiwijaya R, Bachtiar I, Budaya RR, et al. (2026). Two decades of coral monitoring reveal thermal stress thresholds on Indonesian reefs. Biological Conservation 318:111781. DOI