Saudi Red Sea - Thetis (Yanbu)

Setting

A deep offshore wall in the Yanbu area, dived twice with Umluj Dive Center — October 2023 to 34 m and August 2024 — and one of the sites with a per-visit series in the site record. The site is a wall dive: a sheer face dropping into deep blue with overhangs and buttresses, divers hanging off it in the wide-angles, bubble trails rising against the rock (e.g., Image 1, Image 4, Image 8).

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General benthic features

In October 2023 the upper wall was heavily built — a continuous carpet of knobby and columnar Porites, corymbose Acropora, lavender pocilloporids, and Millepora-type plates, with red anthias in clouds over it — and much of it was white (e.g., Image 6, Image 7).

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In August 2024 the same wall photographs as darker, sparser, and more soft-coral- and sponge-dominated: purple and gray soft corals, scarlet and crimson encrusting sponge, orange Millepora, feather-star-studded rock, with hard coral reduced to patches (e.g., Image 2, Image 9).

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A gray-blue bubble coral (Plerogyra sinuosa) with fully inflated vesicles sits at the wall base, and a table Acropora with red sponge growing through it lies on the shoulder above.

Coral cover

Site-level coral cover is 16.1% ± 14.9 across 170 photographs, quoted verbatim from Mayfield, A.B. (2025) Environments 12:248 — Red Sea 2023-24 bleaching; CoralNet point annotation, Appendix A — a manual, diver-annotated CoralNet point count from Anderson's own published work, not a computer vision output and not recomputed here. The two visits are recorded separately and they are strikingly different: 33% cover with 62.1% of coral tissue bleached in October 2023 at 19.9°C-weeks DHW and 30.5°C, against 13% cover with 25.0% bleached in August 2024 at 14.2°C-weeks and 33.5°C. Cover more than halved between the two.

Comparisons with other data

No prior survey data from this site. If you would like to share yours, please email us.