Tragedy at Monk Seal Cave: The Dive of Hayley McCarthy and Stacy Liam

Tragedy at Monk Seal Cave: The Dive of Hayley McCarthy and Stacy Liam
Incident LocationDiver’s Full Name
Bisevo Island, Adriatic SeaHayley McCarthy

Two friends embarked on a celebratory dive in the Monk Seal Cave after being certified as professional cave divers. Enthralled by the beauty of the deep, they decided to dive further for 32 feet before ascending. When one of the divers ascended, she realized that her friend, who had been ahead of her on their way up, had not ascended.

Exploring Monk Seal Cave

Medvedinius Spilia, also known as Monk Seal Cave, holds the esteemed title of being the longest cave found on the splendid Bisevo Island, spanning a remarkable distance of 524 feet. This magnificent cave derives its name from the captivating Mediterranean monk seal, paying homage to the presence of these remarkable creatures.

Situated at the southernmost point of the island is an area known as Biscup or Bishop. It rests gracefully on the border of the breathtaking Treasurevac Cove. The cave has an amazing entrance, reaching an impressive height of 88 feet, making it seem like you’re going to another realm. This passageway, often referred to as Poseidon’s Gate, serves as the gateway into the longest partially submerged sea cave on the eastern side of the Adriatic Sea.

However, from the 1960s on, the monk seals gradually vanished from the Adriatic Sea. Only in recent years have these enchanting creatures made a remarkable return to the Adriatic Waters. Once again, the monk seals chose to dwell within these caves, utilizing them as their cherished spawning grounds.

Visitors and divers can gain access to this cave with a small boat. Within, they are greeted by a beautiful display of light, particularly during certain times of the day, inviting them to behold its complete splendor. However, after a distance of approximately 131 feet, the cave gradually narrows, stopping any further boat exploration.

The Dive Buddies: Haley and Stacy

Hayley McCarthy and Stacy Liam are dive buddies who formed a special bond through their shared love for exploring the underwater world. Their journey began when they crossed paths during their training for open water diving certification. From that moment on, they stuck together, supporting and encouraging each other throughout their diving endeavors. As they progressed in their diving training, Hayley and Stacy were determined to acquire the certification for cave diving.

Together, they made a pact to embark on an extraordinary exploratory dive. Their destination of choice was the renowned Monk Seal Cave because of its beauty and history.

The Dive

On the appointed day, Hayley and Stacy set out for Monk Seal Cave in their privately hired tour boat. At 2:32 PM, they arrived at their destination, ready to embark on their diving journey. With their diving gear in hand, Hayley and Stacy suited up, ensuring that every piece of equipment was securely fastened and in perfect working order.

Their goal for this dive was to reach a depth of 98 feet. Hayley chose twin independent 12-liter cylinders, each filled with nitrox 27. In addition to her primary cylinders, Hayley also carried stage cylinders with different gas mixtures for decompression purposes. She had nitrox 40 and nitrox 80 in these cylinders to facilitate her safe ascent back to the surface.

Meanwhile, Stacy had chosen a rebreather as her diving apparatus. Stacy’s rebreather was configured with trimix 1260 as the diluent. She also carried a bailout gas cylinder filled with nitrox 28. They had dive torches with them because it gets darker inside.

The duo took a deep breath and entered the water, ready to explore the depths of Monk Seal Cave. As they began their descent, the surrounding environment underwent a subtle transformation. The cave ceiling stretched above them while the water’s color became darker. The rocky terrain beneath them created a captivating underwater landscape with no silt deposits that could obstruct visibility. The crystal clear water allowed them to witness the beauty that lay hidden within the depths.

Taking a moment to ensure their equipment was functioning correctly, they paused at a depth of 13 feet for a bubble check, a safety procedure to verify that there were no air leaks or equipment malfunctions. At last, they reached the target depth of 98 feet.

Mesmerized by the beauty of the underwater world surrounding them, Hayley and Stacy decided to explore further. With a shared nod of agreement, they ventured another 32 feet into the depths. Sensing the need to ascend and follow proper decompression protocols, Hayley and Stacy signaled to each other that it was time to start their journey back to the surface.

While ascending for a distance of 16 feet, they suddenly realized that they had strayed from their actual dive path. They had to compose themselves and diligently observe their surroundings. They carefully checked their map to get back on track. They soon managed to find their way back on the correct path and breathed a sigh of relief.

Approximately 32 feet further along their route, Hayley, who was on an open circuit system, deployed a Delayed Surface Marker Buoy (DSMB) which contained a relatively small quantity of gas within it. This is typically done by divers during the concluding stages of their dive. The purpose of the DSMB is to signal their ascent while providing a visual reference point along the line and simultaneously marking their precise position for the surface boat to monitor. It also serves the crucial function of facilitating decompression and ensuring safety stops are efficiently executed.

As Stacy continued her ascent, having already ascended approximately 18 feet from their previous location, she deployed her own DSMB. Upon successfully deploying the DSMB, Stacy noticed that Hayley had managed to position herself approximately six feet above her. Motivated to bridge the distance between them, Stacy swiftly ascended at a faster pace in an attempt to catch up with Hayley.

However, it became surprisingly obvious that Hayley was ascending at an accelerated pace, outpacing Stacy’s efforts to close the gap. Stacy decided to slow her ascent deliberately, reducing her speed. When she reached a point around 82 feet from their starting point, intending to reunite with Hayley, Stacy decided to continue her ascent at a regular pace, believing that Hayley would remain visible along the line of the DSMB. She assumed they would meet up around 39 feet as planned.

As Stacy gradually ascended to a depth of 39 feet, she realized that she and her friend had become separated. But she had observed the necessary decompression stops to ensure her safe return. Having fulfilled the requirements for decompression, Stacy resurfaced and made her way back to the dive boat. Although she was not expecting to meet Hayley up there, her decompression needs would have been greater due to her using an open circuit system.

Hayley’s DSMB caught Stacy’s attention, positioned upright with approximately 50 percent of it submerged. However, a growing sense of concern enveloped Stacy after approximately 35 minutes had elapsed since resurfacing. She requested that the boat move closer, hoping to identify any discernible bubbles that might provide clues about Hayley’s whereabouts. Unfortunately, despite the closer proximity, no bubbles could be detected. This made Stacy worry about Hayley’s well-being and location.

Suiting up again, Stacy dived back into the waters, determined to locate the DSMB situated approximately 65 feet away. As Stacy swam closer to the DSMB, her eyes detected the presence of the reel, but Hayley was nowhere to be seen, leaving Stacy with no choice but to ascend and inform the boat crew about the absence of her friend.

Upon retrieving the reel, an investigation revealed that approximately 22 feet of the line had been unspooled, adding another confusion to the unfolding mystery. Acting swiftly, the dive boat skipper immediately initiated a distress signal, urgently issuing a Mayday call while enlisting the assistance of other people to initiate a thorough surface search. A collective effort ensued as a total of six boats, including one RNLI lifeboat, rallied together. They searched the expansive surface in a desperate bid to locate any trace or glimpse of Haley’s presence.

Despite the relentless search, the anticipated sight of Haley ascending from the depths did not happen. This prompted the deployment of two expert divers who dived in for a search and rescue. After searching, as they dived, Haley’s lifeless body was located at a depth of 72 feet, floating around, a sad confirmation of the fate that had befallen her. Her body was carefully retrieved from the depths and transported to the surface, where the waiting lifeboat stood.

As they witnessed the tragic turn of events, examining Hayley’s diving gear, it was discovered that all cylinders were still filled with gas, and the regulators were found to be functioning as intended, raising concerns for the rescuers about the actual reason for her untimely demise.

With heavy hearts, Hayley’s lifeless body was solemnly conveyed back to the shore. After being examined by medical personnel, it was revealed that she had suffered a heart attack.


What is Monk Seal Cave?

Monk Seal Cave is the longest cave on Bisevo Island, spanning 524 feet.

Who were Hayley and Stacy?

Hayley and Stacy were friends and dive buddies who embarked on the cave dive.

What happened during their dive?

Hayley and Stacy became separated during their ascent, and Hayley went missing.

How was the search conducted?

A surface search involving multiple boats and expert divers was conducted.

What was the cause of Hayley’s death?

Hayley suffered a heart attack, which led to her untimely demise.

Patrick Broin
Patrik, a seasoned cave diver, shares his first-hand experiences and expert insights on the treacherous world of cave diving accidents.
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