Maldives - Vaadhoo Caves

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Part of the regional summaries: Maldives - Central (Male Atolls / Ari / Vaavu) and Maldives

Photo: Anderson Mayfield/Coral Reef Diagnostics

Country

Maldives

Survey date(s)

2017-05-16

Coordinates

4.1270, 73.4540

Coral cover

4.7%^*

Claude computer vision (18 edited photos) · other methods below · median 0.0%

*Based on only 18 reef-habitat photos; this estimate is less certain.

Observations

crown-of-thorns

Heat stress

Most recent heat load record

30.1°C 0.0°C-weeks

26 Oct 2026 · Bleaching Watch

5-year thermal stress load

5-year mean max. degree heating weeks (DHW)

2.2°C-weeksⁱ

2021–2025

NOAA Coral Reef Watch — Maldives 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 info

Maldives (NOAA CRW virtual station)

Photographs

21 shown on this page

Site summary

Read this summary in:

A wall dive built around shadowed overhangs fringed in pale lavender soft corals, more about topography and current-fed fish life than coral cover.

Max. depth dived

32 m

sample-sheet maximum

Sea surface temp. (satellite)

30.0°C

satellite sea surface temperature (SST) on the survey date (NOAA Coral Reef Watch, Maldives), not an in-water reading; it is the warmest-pixel (90th percentile) reading in the station area and can run 1–1.5°C above the reef

Nine independent survey stations shown with the program’s logo — click one to see how far it is from this site.

11 of the 21 photographs on this page are shown beside the text that discusses them under "Site description" below.

Photo credit & attribution

Site description

Setting

An early-morning drop onto a steep wall notched with deep, shadowed overhangs — the "caves" — each one trimmed along its lip with a frilly fringe of pale lavender soft corals that seem to glow against the dark (e.g., Image 2, Image 5).

This is a topography dive: divers hang off the edge for scale, sunbeams rake past the ledges, feather stars and bushes compatible with black coral cling to the face, and clouds of small orange basslets stream along the drop-off where the current delivers breakfast (e.g., Image 1, Image 4, Image 10, Image 12, Image 14, Image 20).

Coral cover

Reference: Claude CV point count (this site's photos)
Coral cover: 4.7% — a blind Claude computer-vision point count of 18 of Anderson's edited photographs (20 points per photo; water, fish, and obstructions excluded). Other computer-vision methods are listed in the method table.

Stressors

During a crown-of-thorns removal survey in May 2017, divers from Coral Reef CPR and Carpe Diem Maldives removed four crown-of-thorns starfish from this reef (Anderson's field sheet; Coral Reef CPR 2017).

Fish and other fauna

Inside one cave mouth, a school of silvery fish mills in the gloom like static on an old TV (e.g., Image 7).

The morning's strangest guest was a remora, caught mid-water threading through a shoal of fusiliers with no shark, no turtle, no host in sight — just a hitchhiker between rides, photographed at the moment of unemployment (e.g., Image 15, Image 21).

Comparisons with other data

Montefalcone et al. (2020) surveyed a station named Vaadhoo Caves, 0.74 km away. Within 5 km, nine independent stations recorded station-year means of 8.8–48% hard coral cover between 2011 and 2019; the nearest, Reef Check at Vadhoo Caves, 0.32 km away, read 13% in 2018.

CV model comparison

Mean 4.7%, median 0.0% across 18 photos.

More info

A 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 info

Other rows are for comparison only and are never averaged. No diver transect exists for these photos, so agreement between rows is not accuracy.

Method	Hard coral cover (%)	Photos (n) ± SE
In-house DINOv3	7.3
CoralSCOP edited	14.8
Claude (edited photos)	4.7*	n = 18 · SE 2.3

The two computer-vision methods differ by 7.5 pp (7.3–14.8%) and read 2.6–10.1 pp above Claude's blind point count (4.7%); the headline is Claude's blind point count because no transect or manual count exists here.

*Based on only 18 reef-habitat photos; this estimate is less certain.

See a more detailed, stand-alone version of this table.

Independent surveys nearby

Data availability near this site
Agency / program	Year(s)	Stations / distance	Link
Montefalcone et al. (2020)	2017–2019	2 stations, 0.74–3.85 km	Records ↓
Reef Check	2011–2019	5 stations, 0.32–3.96 km	Records ↓
Surveyor not identified	2011–2012	1 station, 1.94 km	Records ↓
XL Catlin Seaview Survey	2015–2017	1 station, 1.80 km	Records ↓

Within 5 km, 9 independent survey stations recorded hard coral cover in 19 records between 2011 and 2019. Of the 3 stations surveyed in more than one year, 1 was scored by divers or by people annotating photographs: increased by 26 points between its first and latest surveys. The other 2 were scored by automated image analysis: 1 increased (by 14 points), more than the 7-point method-noise floor; 1 changed by 7 points or less, inside the 7-point method-noise floor (inconclusive). Two stations have the longest records (2 years each); one, transect 37037 (XL Catlin Seaview Survey, 1.80 km away), went from 14% in 2015 to 9.1% in 2017. The most recent nearby survey is from 2019, so these values predate recent heat stress. This site's own estimate (4.7%) sits 4.4 points below the range of these station-year means up to 2 km away (9.1–40%), inside the 7-point method-noise floor (inconclusive); the methods differ, so the comparison is context, not a like-for-like test.

Collected by other programs using different methods (Reef Check uses point-intercept transects; the XL Catlin Seaview Survey uses photo-transects with automated image annotation), so these are context for the figures above, not a like-for-like comparison. Where a station was surveyed more than once, the cell shows either the range of its values or, as a single value, the mean of surveys made in one year. Station names are not dive-site names.

Independent survey data near this site
Agency	Site / location	Date	Hard coral cover (%)	Distance	Link
Surveyor not identified	Emboodhoo	2011–2012	26–40% (range of yearly means; 4 records)	1.94 km	—
Reef Check	Laguna Beyru House Reef	2011	12%, mean of 3 surveys (5.5 m, 8 m, and 10 m)	3.96 km	—
Reef Check	Embudhoo	2012	38%, mean of 2 surveys (5 m and 10 m)	1.86 km	—
XL Catlin Seaview Survey	transect 37037	2015–2017	9.1–14% (2 surveys)	1.80 km	doi:10.14264/uql.2019.930
Reef Check	Embudhu (South Male)	2017	9.4%	1.72 km	—
Montefalcone et al. (2020)	Velassaru	2017–2019	22–48% (range of yearly means; 2 records)	3.85 km	doi:10.3389/fmars.2020.00587
Reef Check	Vadhoo Caves	2018	13%, mean of 2 surveys (5 m and 10 m)	0.32 km	—
Montefalcone et al. (2020)	Vaadhoo Caves	2018	23%	0.74 km	doi:10.3389/fmars.2020.00587
Reef Check	Vellassaru beyru	2019	8.8%, mean of 2 surveys (5 m and 10 m)	3.47 km	—

Data & links

All images from Coral Reef Diagnostics. Data are from Coral Reef Diagnostics and the organizations named in the data sources above.

References

Montefalcone M, Morri C, Bianchi CN (2020). Influence of Local Pressures on Maldivian Coral Reef Resilience Following Repeated Bleaching Events, and Recovery Perspectives. Frontiers in Marine Science 7:587. PDF
Coral Reef CPR & Carpe Diem Maldives Pvt. Ltd. (2017). Crown-of-thorns starfish removal report, North and South Malé Atolls, 13-20 May 2017. PDF
Gonzalez-Rivero M, et al. (2019). Seaview Survey photo-quadrat and image classification dataset. The University of Queensland (UQ eSpace) data collection. DOI