Coral Reef Diagnostics

Taiwan - Lanyu (Orchid Island): Blue Hole (Yeyou large boat harbor)

Reef Check Foundation
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Part of the regional summaries: Taiwan (mainland + offshore islands) and Taiwan

05
Coral Health Index: TBD
Country
Taiwan
Date(s) visited
2008-09-20
Coordinates
22.0550, 121.5040
Approximate position.
Coral cover
48%
nearest station surveyed in the last 10 years, not this site: Reef Check, Beauty Rock station, mean of 2 surveys (5 m and 10 m), 2019-06-30, 1.94 km away; the station's published position is on land
Observations
None tagged; see Stressors below
Heat stress
Most recent heat load record
28.5°C0.8°C-weeks
26 Oct 2026 · Bleaching Watch
5-year thermal stress load
5-year mean max. degree heating weeks (DHW)
12.6°C-weeksi
2021–2025
NOAA Coral Reef Watch — Southern Taiwan 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 infoSouthern Taiwan (NOAA CRW virtual station)
Site summary
Read this summary in:

A single 2008 dive at Blue Hole, a fish-packed cavern and tunnel system rather than open reef. No cover of its own was measured; Reef Check's closest station, 0.67 km away, recorded 14% hard coral in 2009, and a station 1.9 km away recorded 48% in 2019.

Max. depth dived
17.7 m
Sea surface temp. (satellite)
29.1°C
satellite sea surface temperature (SST) on the survey date (NOAA Coral Reef Watch, Southern Taiwan), 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
Bottom time
47 min
in at 16:00

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

One other CRD dive site with its own page within 5 km shown in orange — click a marker to open its page.

Site description

Setting

Anderson's log describes a cavern full of fish at around 45 ft and a series of tunnels — structure, in other words, and no cover measurement of its own was taken.

Stressors

Anderson's dive log for this dive (20 September 2008) describes a cavern full of fish and a series of tunnels and records no bleaching, disease, crown-of-thorns starfish, or other stressor.

Comparisons with other data

The closest Reef Check site, Tudigong Temple, is 0.67 km from this approximate pin; its only survey date, 26 September 2009, recorded 14% hard coral (mean of 2 surveys, 3 m and 6 m; Reef Check data, a separate station, not a survey of this site). The most recent Reef Check survey within 2 km, at the Beauty Rock station 1.9 km away, recorded 48% on 30 June 2019; it is the value shown in the coral-cover tile, and that station's published position is on land. Across Lanyu, Reef Check station-year means ranged 6.3-67% hard coral cover between 1998 and 2019 (source: Reef Check).

Dive record

One dive, 20 September 2008, entering at 16:00 for 47 minutes to 17.7 m, at the site logged as Blue Hole by the large boat harbor at Yeyou on Lanyu.

No underwater photographs from this site are on file.

Independent surveys nearby

Hard coral cover over time — every independent station within 5 km. Programs are shown separately because they use different methods at different stations; the lines are not one comparable series.
0%17%34%51%68%199820082019Reef Check 1998: 6.3%Reef Check 1998: 8.8%Reef Check 2009: 14%Reef Check 2009: 28%Reef Check 2010: 48%Reef Check 2014: 24%Reef Check 2014: 50%Reef Check 2015: 46%Reef Check 2015: 57%Reef Check 2016: 20%Reef Check 2016: 20%Reef Check 2016: 67%Reef Check 2017: 50%Reef Check 2018: 49%Reef Check 2019: 48%Year-averaged across all programs: increasing (+1.99 pp per year; 9 years)
Reef CheckYear-average (increasing)

Within 5 km, 13 independent survey stations recorded hard coral cover in 29 surveys between 1998 and 2019. The one station surveyed in more than one year declined by 2.0 points between its first and latest surveys. The longest record, Beauty Rock (Reef Check, 1.94 km away), went from 50% in 2017 (mean of 2 surveys) to 48% in 2019 (mean of 2 surveys). The most recent nearby survey is from 2019, so these values predate recent heat stress.

Collected by other programs using different methods (Reef Check uses point-intercept transects), 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.

Show all 29 independent surveys
Independent survey data near this site
AgencySite / locationDateHard coral cover (%)Distance
Reef CheckHongtoe19988.8%2.26 km
Reef CheckGeeChang19986.3%, mean of 2 surveys (3 m and 10 m)4.50 km
Reef CheckTudigong Temple200914%, mean of 2 surveys (3 m and 6 m)0.67 km
Reef CheckYeyou200928%, mean of 2 surveys (3 m and 6 m)0.83 km
Reef CheckVirgin Rock201048%, mean of 2 surveys (3 m and 10 m)4.26 km
Reef CheckYeyou Harbor201424%, mean of 2 surveys (5 m and 10 m)0.85 km
Reef CheckHutoupo201450%, mean of 2 surveys (5 m and 10 m)2.35 km
Reef CheckMaiden Rock201557%, mean of 2 surveys (5 m and 10 m)3.34 km
Reef CheckLangdao Harbor201546%, mean of 2 surveys (5 m and 10 m)3.93 km
Reef CheckLand Temple/Earth God Temple201620%, mean of 2 surveys (5 m and 10 m)1.78 km
Reef CheckYeyou201620%, mean of 2 surveys (5 m and 10 m)2.64 km
Reef CheckBeauty Rock201667%, mean of 2 surveys (5 m and 10 m)3.31 km
Reef CheckBeauty Rock2017–201948–50% (range of yearly means; 6 surveys)1.94 km

Data & links

Data on this page are from Coral Reef Diagnostics (the dive record) and the organizations named in the data sources above; Coral Reef Diagnostics has no coral cover estimate of its own at this site.

© Coral Reef Diagnostics.