Exploring the Depths of Britain's Caribbean Territories
The waters surrounding the vibrant coastlines of Britain's Caribbean territories have long remained largely unexplored. Recently, scientists embarked on the first expedition beyond the shallow waters of these islands, revealing an underwater mountain range, a vast "blue hole," coral reefs seemingly untouched by climate change, and previously unknown marine species.
For six weeks, researchers operated continuously, deploying cameras and specialized equipment capable of withstanding extreme water pressure to depths reaching 6,000 meters (19,700 feet).
Navigation around the Cayman Islands, Anguilla, and Turks and Caicos was challenging due to reliance on outdated maps, some decades old, containing significant inaccuracies and missing entire regions.
The UK Centre for Environment, Fisheries and Aquaculture Science (CEFAS) has shared exclusive footage and findings from the expedition with .
The UK government holds shared responsibility for conserving the natural environment of these islands, where up to 90% of Britain's unique species reside within these and other British Overseas Territories.
Scientists emphasize the urgency to protect this "relatively pristine" ecosystem from climate change and pollution threats.
"This is the first step into environments people have never seen, and in some cases didn't know existed," said Prof James Bell, who leads the expedition aboard the British research vessel RSS James Cook, accompanied by scientists from the three islands.
"Just yesterday we found a kind of type of swimming sea cucumber, and we still don't know what it is," he added, describing the biodiversity encountered as "really, really astonishing."
Unique Species and Extensive Biodiversity
The Cayman Islands, Anguilla, and Turks and Caicos are home to 146 species endemic to these territories. The current expedition is expected to expand this list further.
Researchers documented nearly 14,000 individual specimens representing 290 distinct marine species, though further scientific analysis is required to confirm these findings.
Among the discoveries were a pelican eel featuring a glowing pink tail that flashes red to attract prey, a barreleye fish with tubular eyes oriented upwards to detect silhouettes of prey, and a dragonfish equipped with a luminous rod beneath its chin.
Mapping Uncharted Underwater Terrain
While navigating an uncharted underwater mountain known as Pickle Bank, Prof Bell remarked on the difficulty of determining proximity to the formation, stating,
"We're not sure how close to it we are. It's quite difficult to map it without running the risk of running aground."
The team ultimately determined that Pickle Bank, located north of Little Cayman Island, rises from a depth of 2,500 meters (8,200 feet) to approximately 20 meters (65 feet) below the sea surface.
Footage reveals a vibrant mountainside adorned with bright blue, yellow, and orange hues, teeming with life. Golden coral towers grow alongside coral formations resembling large brains.
Fish were observed darting among gorgonian whip coral, alongside jelly-like orange sea sponges near black coral.
Pristine Coral Reefs and Environmental Significance
The expedition uncovered one of the healthiest and most diverse reefs in the region, free from the stony coral disease that has devastated much of the Caribbean. This reef's depth and the steep slopes of the mountain likely provide natural protection.
Deep-water, or mesophotic, reefs are typically too deep to be affected by rising ocean temperatures caused primarily by climate change, which has damaged 80% of the world's corals since 2023.
Advanced Technology for Ocean Mapping
Using deep-sea cameras and echo-sounders lowered from the ship, researchers mapped nearly 25,000 square kilometers (9,700 square miles) of the seafloor and captured 20,000 photographs, including images of glowing lantern fish and alien-like cephalopods.
Prof Bell noted the contrast between our knowledge of extraterrestrial surfaces and our own oceans, stating,
"We know the surface of Mars or the Moon better than we know the surface of our own planet. You send a satellite around them and map them in a few weeks.
We can't do that for our ocean. We have to map it bit by bit using acoustic instruments on ships."
Discoveries in Turks and Caicos and Other Locations
In Turks and Caicos, the team identified a previously uncharted, extremely steep mountain ridge rising 3,200 meters (10,500 feet) and extending 70 kilometers (45 miles) along the seabed west of Gentry Bank.
They also discovered a massive vertical sinkhole, or blue hole, located 75 kilometers south of Grand Turk Bank. This formation resulted from the collapse of a cave.
"Imagine taking an ice cream scoop out of the sea-floor. That's what we saw - a crater about 300 meters (980 feet) wide to 550 meters (1,800 feet) below sea level," Bell explained.
The steep walls of this blue hole may make it the deepest in the Caribbean, rivaling Belize's renowned Great Blue Hole.
While blue holes typically lack life, cameras lowered into this sinkhole revealed small sponges, a species of urchin known as large spatangoid, and a variety of fish species.
Approximately 25 kilometers (15 miles) north of Anguilla, following reports from local fishers who had retrieved coral fragments, the team confirmed the presence of a 4-kilometer (2.5-mile) reef featuring coral mosaics growing within sponge "gardens."
They also discovered black coral specimens potentially thousands of years old, among the oldest ever recorded.
"It tells us that these environments are really pristine and healthy," Bell stated.
Ecological Importance and Future Applications
Scientists are particularly interested in deep-water areas and steep underwater mountains because these features can channel nutrient-rich waters to the surface, creating feeding grounds for marine animals and valuable fishing locations.
Onboard the research vessel, CEFAS collaborated with environmental experts from the Cayman Islands, Anguilla, and Turks and Caicos. These partners will utilize the expedition's findings to enhance biodiversity management plans and explore new fishing opportunities for local communities.
"Our islands were literally born from the sea. But when it comes to our offshore environments, we really haven't had a chance before to discover what's out there," said Kelly Forsythe from the Cayman Islands Department of Environment.
The island governments participated in this research as part of the Blue Belt Programme.
The data collected will assist the UK in meeting its legally binding United Nations commitment to protect 30% of the world's oceans by 2030 through designated Marine Protected Areas.
"Anyone can draw a box on a map and say, 'That's a marine protected area,'" Bell explained.
"But unless you know what's in it, you don't know if that's useful at all."
