Cayman Islands Department of Environment (DoE) team, left to right: Matt Southgate, Claire Fletcher, Meghan Ehman, Kelly Forsythe, Paul Chin, Sabrina Douglas, Justin Porter, Jane Haakonsson, Photo: Lawrence Eagling/Blue Belt.
The Cayman Islands are renowned for their clear waters and vibrant near shore coral reefs, yet far offshore lie little‑explored underwater banks and deep sea habitats. Over 12 days onboard the RRS James Cook, eight scientists from the Cayman Islands Department of Environment (DoE) joined the Blue Belt Programme’s Beyond the Reef Expedition to map thousands of square kilometres of seafloor, study rare deep ocean species, and capture imagery from depths of nearly 3,000 metres — producing one of the most detailed offshore surveys in Cayman’s history. The footage and data gathered have provided valuable new insights into Cayman’s biodiversity, fisheries, and unique offshore ecosystems.
During the expedition, the team have:
Mapped over 11,000 km2 of seafloor. Processed nearly 900 litres of water and collected 988 samples; Explored remote banks and ridges, including Lawfords Bank, Pickle Bank and 60‑Mile Bank, uncovering unique species, dramatic underwater landscapes, and rich biodiversity. Identified over 1,000 specimens, covering nearly 200 species in offshore waters from depths ranging from surface to 1,200 metres. Taken over 9,000 photos from surface to 2,800 metres – the deepest depths reached by our tow camera during the whole expedition. Collected 161 hours of video footage. Paul Chin, Serena Douglas and Claire Fletcher from Caymans DoE identify specimens collected with the trawl net. Photo: Lawrence Eagling/Blue Belt ProgrammeMapping Caymans offshore banks
Nearly half of Cayman’s coastal/near shore waters are protected through the Marine Protected Area network, representing under 1% of Cayman’s total Exclusive Economic Zone. While near‑shore reefs are well studied, the deeper underwater banks surrounding the main islands of Grand Cayman, Little Cayman and Cayman Brac remain largely understudied, making this expedition a crucial step in understanding these hidden ecosystems.
Using multibeam echosounder, the expedition has created detailed maps of over 11,000 square kilometres of Cayman’s seafloor, taking some of the first ever photographs of Lawfords bank and the unnamed "shark" ridge. One of the most interesting findings for the team was how much the ecosystems differed between each of the banks, some located no more than a few kilometres apart.
By understanding the unique and defining features of each bank, the team were able to better understand why these ecosystems vary. One possible factor is upwelling, the process where cool, nutrient‑rich water rises and mixes with warmer surface waters. This process could be why Pickle Bank and 60‑Mile Bank are so biodiverse — their geology and the ocean current create ideal conditions for nutrient‑rich waters to reach the surface and support a variety of different species.
Kelly Forsythe, Blue Belt Programme Officer, looks at maps of the area. Photo Lawrence Eagling/Blue Belt Programme.“It’s been amazing to see the ridges and offshore banks of the Cayman Islands come to life. I came into this expedition thinking that our offshore reefs would be very much the same as our near shore reefs, but to our surprise, they are all are unique. The findings are spectacular and exceeded our expectations.”
Kelly Forsythe, Blue Belt Programme Officer, Department for Environment, Cayman Islands
Lawfords Bank
Just 10 miles northeast of Cayman Brac, the first ever images were taken of Lawfords Bank revealing a wide, sandy plateau rising sharply from deeper waters. Underwater camera images revealed an array of echinoderms (sea cucumbers, urchins and starfish), and mid‑water trawls revealed a diverse mix of species including shrimp, enope squid, and the larvae of puffer fish, pipefish, triggerfish and even the striking fangtooth fish.
Pickle Bank
One of the most spectacular discoveries came from Pickle Bank — a seamount rising from 3,000 metres deep to just 30 metres below the surface. Its upper slopes held colourful, thriving mesophotic reefs, which transitioned into rocky habitats which were home to remarkable deep‑sea species. In a single day, researchers recorded over 260 specimens, including:
The Jewel squid (Histioteuthis reversa),known for its bright jewel like appearance due to specialised organs that emit bioluminescence. An unidentified sea cucumber, but one of only two species of sea swimming sea cucumbers Larvae of the rare Gibberfish (Gibberichthys pumilus) usually found in much deeper waters. Cuban dogfish, hermit crabs, spider crabs and abundant shrimp Several Caribbean reef sharks swimming along the slopes.The Unnamed Ridge (“Shark Ridge”)
Layered rock, likely the result of solidified larva, was the defining feature of this seamount several miles north of Grand Cayman. Although frequently visited by tagged sharks, none were observed during this expedition. However, the team did capture evidence of deep dwelling eels and Batfish larvae, a type of flat disk-shaped angler fish — potentially the first ever recorded in the region.
60-mile bank
The smallest of the offshore banks, with a triangular shape and unusually flat surface found 60 miles from Grand Cayman, this bank is well known to local fishers, but has never been seen by the wider public. The expedition found:
Mesophotic reefs giving way to coarse gravel and dramatic ridges Several Misty grouper and deepsea snapper at around X depth. A glass squid (Cranchiidae), with see through body and large luminescent eyes. Giant isopods – similar to woodlice but many 100s of times larger in the deep-seaCoral diversity
Coral reefs in Pickle and Lawfords Bank. Photo: Cayman Islands Government.Coral experts from the DoE and the team were delighted to see that the Cayman Islands’ offshore banks revealed a remarkable refuge for coral health and biodiversity. In Pickle Bank, the team were surprised to see healthy reefs between the near surface and down to 200 metres deep. Crucially, these habitats appear to be free from stony coral tissue loss disease, which has had a huge impact on shallower reefs around the Cayman Islands, as it has in many other locations throughout the Caribbean. Towed camera images revealed a rich community of soft corals, stoney corals and slow growing black corals. At around 400-700metres, the team also discovered some ancient reef terraces —some potentially millions of years old—and still intact enough for scientists to identify their original genus.
At 60 mile Bank, the shallower reefs were dominated by sponges and algae but also abundant rose corals, a type of brain coral rare to the Cayman Islands.
Across the wider Cayman deep reef landscape, researchers have also documented exceptional diversity in deep lace corals, sea fans reaching depths of 600 m, and delicate glass sponges, highlighting the ecological richness of these offshore environments.
Meghan Ehman, Reef Conservation Assistant, from the Cayman Islands DoE reviews tow camera footage with the team. Photo Lawrence Eagling/Blue Belt Programme.“It has been fascinating getting to learn more about the deep-sea corals and sponges that I know very little about, and I’ve noticed my ID skills improving with each subsequent camera tow. I’m looking forward to starting the analysis of these images to obtain a better understanding of the habitat composition of Cayman’s deep-sea waters.”
Meghan Ehman, Reef Conservation Assistant, Department for Environment, Cayman Islands
Water quality
To understand how the ocean changes with depth, the team also deployed a CTD (conductivity, temperature and depth) device, which is lowered from the sea surface down to the seafloor. Along the way, it records temperature, salinity and oxygen levels, and captures water in specialised bottles at precise depths. This allows scientists to build a detailed picture of water chemistry, search for signs of nutrient pollution, and detect environmental DNA — tiny particles that reveal which species are present in these waters. In total, water samples were collected from 14 locations, drawing nearly 900 litres and gathering 988 samples from depths reaching 1,400 metres. Once analysed back at Cefas laboratories, the results will provide vital data on water quality and how nutrient pollution and climate change may be impacting Cayman’s marine environment.
Left: CTD device being deployed Right: Justin Porter from Cayman Islands DoE filters water and collects samples from the CTD machine. Photo Lawrence Eagling/Blue Belt ProgrammeFisheries
A major aim of the expedition was to map habitats used by economically important deepsea fish, including Nassau grouper and several snapper species. With the help of underwater cameras, the team were able to corroborate local fishers’ reports of Nassau grouper and snapper presence in the areas around Pickle Bank and Lawfords Bank. Interestingly, 6 snapper species were recorded, two more than expected. Baited Remote Underwater Video cameras (BRUVs) and Bathysnap cameras also captured apex predators including Cuban dogfish, Caribbean reef sharks and elusive Oceanic Whitetip sharks. These were encouraging signs to the team of a functioning and healthy ecosystems — crucial when considering locations for future fisheries management.
Left to right: Larvae of the rare Gibberfish (Gibberichthys pumilus) usually found in much deeper waters, deep sea snapper, unidentified sea cucumber, larvae of puffa fish, pipefish, triggerfish and fangtooth fish. Photos: Lawrence Eagling/Blue Belt and Cayman Islands GovernmentSeabirds
Two seabird experts form DoE spent each day of the expedition scanning the horizon from the bridge of the James Cook to document Cayman’s prolific seabirds. While their on land work focuses on monitoring key nesting sites for species such as Red-footed Boobies, Brown Boobies, and Magnificent Frigatebirds, offshore monitoring offered vital new insights—especially for young birds that are far harder to track after leaving the nest.
Across 31.5 hours of surveying over 143 miles, the team recorded 91 birds from nine species. Brown Boobies, Red-footed Boobies, and Magnificent Frigatebirds were the most frequently sighted, sometimes as far as 150 miles from their nesting grounds. Birds were often seen actively foraging around offshore banks, suggesting these features are important feeding areas.
As one the first offshore seabird survey in Cayman waters, it has provided valuable baseline data for future studies and will support detailed bird density modelling and a deeper understanding of how seabirds use the offshore environment.
Matt Southgate and Jane Haakonsson, seabird experts from Cayman Islands DoE on the bridge balcony of the James Cook observing seabirds. Photo Lawrence Eagling/Blue Belt Programme.Next steps
With a wealth of findings, the next steps will be for the team to analyse and share the data. The findings will help provide the baseline data needed to support the DoE's marine protection, water quality and fisheries management plans, helping the islands progress towards a global target of protecting 30% of the ocean by 2030. Some of the species collected were also donated for further study and will potentially be rehomed at the Cayman Islands' Natural Museum.
Building on a successful public engagement campaign and public tours of the James Cook vessel, the DoE team will also be holding a webinar series and a district library tour to share the expedition's findings with the Cayman community to highlight the importance of Cayman's offshore and deep sea environments to support healthy fish stocks, protect vulnerable seamount environments and support local livelihoods.
Keep following the Blue Belt for more updates on the data collected and how it will be used.
Representatives from Cefas, MMO and the Caymans DoE onboard the RRS James Cook. , Photo: Lawrence Eagling/Blue Belt. seen at 14:30, 10 March in The Blue Belt Programme.