In August 2025 a glass sphere is lowered to the seabed off Benin, more than 50 metres down. Inside is a video camera. Next to it a sensor logs temperature and oxygen. On the bot lie large blocks of rock, and on the rock grow fan-shaped corals. Fish swim around them.

In 1963 and 1964 ORSTOM, the French overseas research agency, was working off Benin. It is now called the Institut de Recherche pour le Développement. The agency reported a coral reef between 52 and 56 metres deep on Benin’s continental shelf. The reef was presumed dead. Its state stayed unknown for sixty years.
Coffi Gérard Franck Zinzindohoué, of the Beninese institute IRHOB, went back to look for it. With him were colleagues from Benin, the Alfred Wegener Institute and GEOMAR in Germany, the University of Porto and the National Geographic Society. The paper came out open access in Frontiers in Marine Science on 20 July 2026. The publisher’s press release is from the same day, and ScienceDaily republished it on 14 September.

In April and May 2025 the team towed a side-scan sonar, an instrument that maps the seabed from sound echoes. It ran 35 transects totalling 11.5 kilometres, over a stretch about 7 kilometres long from west to east. The sonar found two zones of hard bottom, 5.4 kilometres apart. In the first, some structures reach 208 metres in length and 7.4 in height. In the second, one structure is 275 metres long and rises 10.3. The team then sent an underwater drone down twice, and the Deep Sea Camera System of National Geographic five times.
At 54 metres the footage shows live corals on rock. Most are octocorals, corals whose polyps have eight tentacles. The authors count at least six octocoral forms and at least two black corals, the antipatharians. The hard corals that build reefs are rare, small colonies with pale tissue, from white to violet. There is no growing carbonate framework. The authors speak of a coral garden, not a reef. Eight fish species swim around them, including Holacanthus africanus and Chaetodon robustus.
The water at the bottom changes a lot. Between 50 and 60 metres the recorded temperature ranges from 18.9 to 25.9 degrees. Oxygen saturation runs from 44.5 to 92.5 per cent. The authors explain that the corals grow inside the thermocline, the layer where temperature drops quickly with depth.

The press release describes an apparently healthy reef with eight types of coral and eight fish species. The paper describes an octocoral garden. The eight corals are forms told apart in the footage, not identified species. In some areas the video shows dead colonies covered by hydroids and serpulids, worms that live in chalky tubes. The study does not measure coral cover and does not assess health.
The work is exploratory and says so. It was meant to detect and confirm, not to measure. No physical samples were taken. Video inspection covered only the first reef complex, because of logistics and budget. The sonar covered only part of the area described in the 1960s. The authors write that this is, to their knowledge, the first record of live mesophotic corals on the Gulf of Guinea shelf. Mesophotic means the twilight band between full light and darkness, roughly 30 to 150 metres. The authors list bottom-contact fishing among the growing pressures on the shelf.

The research was funded by a National Geographic Society grant. The authors declare no competing interests and state that generative AI was not used to write the manuscript. The journal notes that the alt text of the figures was generated with AI support and checked by the authors where possible.
The depth is the one marked in 1964. On the rock blocks the corals are alive.

References
Zinzindohoué C.G.F., Midinoudéwa H., Akondé B.-N.C., Sohou Z., Schauer U., Fiedler B., Rajan K., Giddens J., «First evidence of live mesophotic coral reefs on the Benin continental shelf», Frontiers in Marine Science, 13, 1848226, 20 July 2026, open access under CC BY. doi: 10.3389/fmars.2026.1848226
Frontiers, press release of 20 July 2026, «Underwater drones discover coral reefs off Benin, long presumed dead, teeming with life», republished by ScienceDaily on 14 September 2026 as «A coral reef thought dead for 60 years is teeming with life» (secondary source).