Sitting on the edge of a small dive boat, clad in a thick wetsuit and bulky scuba gear, every movement feels awkward and cumbersome. But with a deep breath, I roll backwards into the Atlantic Ocean.
The instant rush of cool water is a relief, and the heaviness of the equipment eases as gravity releases its grip. I float, weightless and free, settling into the ocean’s familiar embrace.
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Taking one last breath from above, I prepare to sink, deflating my jacket, exhaling and descending into a vast blue silence. As I adjust my equipment and acclimatise to this alien realm, a dark silhouette glides beneath me. Then another.
I lift my gaze and let out a muffled squeal into my regulator. I am surrounded. A swirling mass of olive-green wings moves in hypnotic synchrony, eyes fixed inquisitively on my presence.
I am at Ambrósio, a small seamount off the southern coast of Santa Maria in the Azores, a place whose name fittingly translates as ‘divine’ in Portuguese.
Beneath this calm surface, a rare spectacle unfolds each summer: aggregations of sicklefin devil rays, their otherworldly schools of more than 50 individuals gliding gracefully through mid-Atlantic waters.
Unlike their more familiar manta cousins, devil rays (of which there are seven species in total) are notoriously shy.
Yet at Ambrósio, they approach divers with measured curiosity, holding eye contact and manoeuvring with their cephalic fins – those distinctive, paddle-like appendages on either side of the head – to maintain position in the water.
Ambrósio’s rays
Ana Filipa Sobral (known as Pipa), founder of Manta Catalog Azores, can still remember the moment she first saw them.
“I was amazed by their behaviour and how they’re so curious towards divers,” she says. “I was not expecting them to be so friendly. Every encounter I’ve had since has been just as special as that first one.”
On a calm, sunlit day at Ambrósio, you truly understand the meaning of ‘Azorean blues’. Golden shafts of sunlight pierce the seemingly endless deep, illuminating the rays as their golden wings cruise beneath you.
If you’re lucky, a pod of Atlantic bottlenose dolphins will streak past, their distinctive clicks and whistles echoing long before you spot them. Occasionally, a whale shark drifts silently through the scene, the world’s largest fish an awe-inspiring presence.
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Pelagic predators patrol the depths, drawn to the nutrient-rich currents that make this seamount – invisible on maps and marked only by the occasional bobbing dive boat – a biodiversity hotspot.
Even the smallest details, like the shimmer of microscopic plankton swirling in the current, remind you that this is a world completely apart, one that we land-bound humans can only glimpse momentarily.
For a few months each year, from June to early October, Ambrósio becomes one of the world’s only reliably accessible aggregation sites for sicklefin devil rays. But why they choose Ambrósio remains a mystery.
“We do know we have a lot of pregnant females. All the animals we see are adults, but we don’t see any juveniles,” says Pipa. “Ambrósio might be a pit stop on their migration, or it could play a role in reproduction or feeding. We still don’t know for sure, but the probability of encountering rays here is high.”
What are sicklefin devil rays?
Sicklefin devil rays are among the ocean’s most graceful yet little-known megafauna. Olive-green to brown on their dorsal side, with dark ventral markings and distinctive grey-and-white belly patterns – each unique, like a human fingerprint – they can reach a wingspan of up to 3.4m.
These rays are the deepest documented divers among manta and devil rays, plunging 2,000m down into near-freezing waters.
Their brains are kept warm at such extreme depths by a specialised network of arteries known as a rete mirabile, which enables them to forage efficiently in the deep scattering layers – dense bands of small organisms that migrate vertically in the water column.
Despite their size and elegance, the sicklefins face immense challenges. Their reproductive rate is agonisingly slow: a female produces a single pup every few years, with youngsters reaching maturity after around a decade.
Populations have plummeted across the Indian, Pacific and Atlantic Oceans due to targeted fishing, bycatch and international demand for their gill plates – used in soups and tonics in the Asian medicine trade.
In response to this global decline, the species was assessed as Critically Endangered by the IUCN in October 2025.
Just a month later, at CITES CoP20 – the 20th Conference of the Parties to CITES, where governments decide how international wildlife trade is regulated – delegates voted by consensus to uplist all manta and devil rays to Appendix I, granting the highest level of international protection and banning all commercial trade in their products.
While this landmark decision marked an unprecedented moment of global unity, it emphasised the precarious reality these animals currently face – their survival still hangs by a thread.
“Manta and devil rays face a number of direct and indirect threats,” says Pipa.
“By far the most concerning is overfishing and fishing-related mortality. These are highly mobile and migratory animals. Even if they don’t face the same level of threat in the Azores, the same individuals can be fished elsewhere. We need to understand their movements to protect them effectively.”
Saving sicklefin devil rays
Pipa’s journey to the Azores began with a passion for marine life, nurtured by growing up on the coast of Alentejo, south of Lisbon. This led to her becoming a marine biologist and, after working on whale shark and manta ray conservation projects in Mozambique, she moved to the archipelago in 2011 for her master’s degree.
She quickly realised that knowledge about the ecology and biology of the sicklefin devil rays was limited, which presented her with a research opportunity.
“I started hearing about diving trips to see groups of devil rays,” she recalls. “And I became aware that it was a species we don’t see very often, especially in groups. When I realised they had patterns on their bellies, it inspired me to try photo identification. That’s how Manta Catalog Azores started.”
Since 2012, Pipa has been building a global-first photographic database for manta and devil rays, which now holds records of 339 individuals, documenting their returns, growth and movements. Some reappear year after year, revealing patterns in site fidelity, migration and reproductive cycles.
Pipa’s research combines a range of innovative techniques. She collects small skin samples to study the genetics of the sicklefins and understand how populations in the Azores are connected to other regions of the Atlantic.
In collaboration with Oceanário de Lisboa, she also uses a tool called stereo-video photogrammetry, which enables her to measure the wingspan of a ray swimming in front of the device, tracking growth and determining maturity.
Soon, Pipa hopes to introduce contactless ultrasonography, a non-invasive technique recently applied to manta rays, which allows researchers to scan the rays’ reproductive organs directly in the water.
“It’s very important to understand how often these animals are getting pregnant and how often they return to the Azores,” says Pipa.
“Ultrasonography will let us study their reproductive biology in a way that hasn’t been done before for this species.”
For Pipa, the work with sicklefin devil rays is personally meaningful. “I think what makes me so passionate about this work is that we’re dealing with species that are really endangered, but there’s still so much we don’t know about them,” she says.
“Here, we have an amazing place to gather information on these species that will be crucial not only locally but globally. We can actively contribute to the wider knowledge of the species and towards its conservation.”
While Pipa’s work focuses on research, she has also invested her time in community engagement. Citizen science is central to the project in that divers contribute photos and observations that expand the catalogue beyond what a single team could achieve.
Responsible tourism is encouraged, guided by codes of conduct developed with the Manta Trust, ensuring interactions with the rays are safe for both animals and humans.
“It’s about mutual respect and ensuring that tourism supports conservation, rather than threatening it,” says Pipa.
She also highlights the power of human connection to inspire conservation.
“I’ve been very focused on research, but one of the things that gives me joy nowadays is going out on the boat with people who have never seen these animals before. From the moment they get out of the water following an interaction, there’s no way they’re not going to be ambassadors for conservation. When you establish that connection, that’s what really gets to people.”
By focusing on the sicklefin as a flagship species, the ripple effects benefit the entire ecosystem.
“If we apply protections for sicklefins here in the Azores,” says Pipa, “we contribute to the conservation of all the other species that depend on the same area.”
The Critically Endangered status of the sicklefin devil ray, alongside the CITES Appendix I listing, underscores the species’ vulnerability.
“Appendix I protection is essential,” stresses Pipa. “Without it, we risk losing these animals before we ever understand their full life history. We can influence what happens locally but these animals cross international boundaries. Conservation needs to be global.”
Long-term monitoring in the Azores is helping to fill knowledge gaps, yet uncertainties remain. Pregnant females dominate the summer aggregations but juveniles are never observed, raising critical questions about nursery habitats and juvenile survival.
Every individual in Pipa’s catalogue represents a vital part of a story still being written. The path forward is challenging but clear: multiply scientific efforts, strengthen national protections and ensure the world commits to enforcing the new international legislations.
“Sicklefins are remarkable animals,” says Pipa. “Their intelligence and curiosity stay with you. When they choose to approach and investigate you, it leaves a lasting impression.”
As I ascend from my dive, my eyes follow the hypnotic silhouettes as the rays disappear into the blue abyss. I linger for as long as possible, reluctant to leave this fragile, beautiful world.
Surfacing, I feel a mixture of elation, mourning for the challenges these iconic rays face, and fierce hope for their future.
Top image: sicklefin devil rays in the Azores. Credit: Reinhard Dirscherl/Getty Images
