Broken records:1
Record:Cave diving depth exploration - 308m
Location:Font Estramar, France
Holder:Frederic Swierczynski

Journey to -308 m world record

A new cave diving exploration world record has been set. During an epic 7-hour dive in the Font Estramar of the Eastern Pyrenees, speleonaut Frédéric Swierczynski from Marseille reached an astonishing depth of -308m!

I am below 260 meters underwater; my discomfort in my eye finally stops, and I can see clearly. I decide to make a quick assessment of my situation: I am conscious and choose to continue moving forward while laying the line. A vertical shaft appears, and I can see the gallery continuing to descend even deeper. The tunnel, made of scoriaceous rock, is vast and disappears into the darkness. I’m the first person here, alone. I drift into the blue night, with the only point of reference being the sound of my breathing roaring through the canisters of my rebreather and the motor of my DPV. I feel good, extraordinarily lucid.

I secure the line to a carved stone; my hands tremble not only with excitement but also due to symptoms of ‘HPNS,’ the dreaded high-pressure nervous syndrome. Despite this, I continue, feeling liberated in this immense aquatic clarity. The atmosphere is otherworldly. I pass by a bed of sand, rippled by the current. Ahead and below me lies a vast and expansive chamber.

Glancing at my timer: 400 minutes of decompression… Fred, it’s time to head back! I’m 50 years old, and today I’ve reached a depth of 308 meters, setting a new world record. Yet, at this moment, I haven’t fully comprehended it. I’ve never been one to base decisions solely on numbers; for me, it’s about the experience, the sensation, the feeling… something exciting.

Progress of the expedition through Frederic's eyes

T minus 10 minutes before the start of the dive
It's been an almost sleepless night. I managed to grab some sleep, but my dreams lingered. The same recurring images, nothing really new. For at least two weeks, my nights have been consumed by meticulously replaying every gesture, every second of that dive. Living on credit in the deep darkness, optimizing every instrument control, visualizing myself navigating the distant gallery, relying on that precious yellow guideline... Beneath the tranquil, transparent blue surface, green algae sway, revealing the current emanating from beneath the earth. Where does this mysterious river originate? As I prepare my equipment by the spring's edge, attempting false cheerfulness, I engage in conversation with veteran deep divers who have come to lend their support. We reminisce about the heavy, open-circuit diving operations from just a few years ago, involving dozens of tanks and days of preparation, contrasting with how I now manage it all in just 20 minutes! I reminisce about the past months: the endurance races in Marseille's Calanques, hours of breathless exertion on the slopes, kilometers traversed through pine forests, scrublands, and rolling limestone scree. And then, the countless deep training dives, here in the warm waters of the Catalan country, plunging down to the -260m zone. These dives aimed to acquaint myself with the underwater topography, navigating the flooded gallery stretching over a kilometer, and perhaps to acclimatize both body and mind. I meticulously refined my decompression curve, aiming for the most precise adjustment possible: minimizing dive time without compromising safety. I adapted my equipment in minute increments, striving to merge seamlessly with the environment, making its challenges my own. Unbeknownst to my conscious self, my body had already made the decision to venture into the unknown, beyond the -300m mark.
T 0 - Here we go!
The DPVs and rebreathers are submerged, meticulously set timers syncing with other divers joining me at the -120m decompression stops. Heated underwear, drysuit - getting help to seal it while I adjust equipment in the water basin, my body halfway submerged. Harnesses, fins, rebreathers - a ritual repeated over the past months. I cannot afford to overlook anything; it's all going to happen in a flash. Each piece of equipment must respond instantly to my needs. The mask - a precious necessity. I rinse it, adjust it meticulously, and then I'm off. The aquatic horizon appears blue, kissed by streaks of sunlight. A black archway reveals itself within the gray rock. I descend into the vertical shaft that follows, allowing myself to be swallowed by the night. Equalizing my ears, ensuring the drysuit fits snugly, rebreathers' lungs emptying, the hiss of the inflators—a battle against pressure unfolds! The DPV propels me into the submerged gallery at over fifty meters per minute. I seize the moment to glance at the rebreather displays, checking the partial pressure of the oxygen mixture I'm breathing. It's crucial information. I can't divert my eyes from these indicators; it's the only way to prevent potential poisoning.
T+5 minutes - On the way…
My vessel maintains a steady cruising speed, led by a Seacraft scooter ahead, towing me while another serves as a backup, secured to my back. My headlights pierce the distance as the crystal-clear water reveals passing walls. The automated control of my instruments is in place. I navigate above the guide cord installed in the main gallery, beneath the vaulted arches stained with iron and manganese oxides: hues of rust, brown, yellow ochre, deep black, and red clay. Eroded mineral structures, sharp as razors, intersect secondary galleries, and the current's direction occasionally plays tricks on us. Font Estramar resembles a complex labyrinth of corridors and dead ends, where losing your way is not an option. I await Patrice Cabanel, following me on his double DPV. He speeds past me, diving much deeper into the expansive vertical well to capture a few videos as I continue my journey.
T+8 minutes - Jump
Descending 60 meters. The actual dive commences. Final checks precede the big jump: activating the powerful dive lights and starting up all equipment that will encounter pressure at depth. It's the last feasible moment before the impending darkness... I prepare myself - it's time to jump!
T+10 minutes - Around -200…
At -100m, I meet Patrice, camera in hand, eagerly awaiting my arrival. He joins me in the descent! -150m, -170m: we accelerate! Swiftly. Perhaps too fast. Like two bikers racing on a vertical track, each trying to outpace the other... He remains close behind, but the maximum test depth of his scooters becomes critical at -180m. I signal to halt him—I don't want his vehicle to implode under the extreme pressure! The memory of the Finnish diver torn apart by his scooter lingers in my mind; I was there to investigate the accident at the request of French authorities. His body remains in that cavity, now his underwater tomb, buried beneath 200 meters of water. I continue my descent, the haunting echoes of crazy organ music reverberating in my head. As Patrice Cabanel recalls: “What's just a little over halfway for Fred represents an immense leap for me. I'm at a depth of 190m, watching him sink further. It's surreal, seeing him surpass 200m and vanish from my sight…”
T+14 minutes - Dazzled
As I continue my descent, the rock formations become lighter, indicating a shift in geological layers—it's as if I'm traveling back in time. I'm approaching the horizontal section of the tunnel, fluctuating between -250m and -260m—a familiar place from my numerous training visits. A round trip usually adds an extra hour to my decompression, but today, I anticipate it'll be much longer, as I'm going deeper. Reaching the bottom of the well at -260m, I stand up and suddenly experience an unfamiliar discomfort: a dazzling sensation. The floor of the submerged horizontal gallery appears flooded once again; it's like an illuminated sea, shimmering with reflections. I move forward as if in a dream, feeling disoriented. In the professional field, a compression at -300m considered 'quick' takes... 24 hours! However, there are challenges associated with compression in a bell or diving box, particularly the gas heating issue, which needs time to cool. Such problems aren't faced by a scuba diver underwater. But today, this isn't just training. The quick descent with Patrice has likely accelerated my usual speed. I may be paying the price for it now.
T+16 minutes - High Pressure Nervous Syndrome
The discomfort dissipates as abruptly as it arrived, and my vision returns. It seems my horizontal journey to the lip of the terminal shaft has revitalized me. Ahead, a black abyss. No more lifeline! I must secure my own reel and ensure the line's safety. My hands tremble... HPNS, it's not uncommon. Over more than 12 years of deep dives below the -200m mark, it's become a familiar companion, no longer surprising me.
T+? minutes - Sleepwalking
I've lost track of time; I'm in a state of ecstasy. The moment I've waited for, perhaps more than 6 months—or is it 20 years?—has finally arrived. My scooter's at a low speed, the yellow line unwinding steadily, and my body's 'trim' is perfect. Balance and positioning in this liquid realm are crucial for survival; they minimize physical exertion and, consequently, metabolism. With wide-open eyes, I absorb the unknown surroundings passing by me; the receding blue horizon guides my progress, gestures, and decisions. Now, it's the exploration itself that drives my dive. I glide into an increasingly expansive chamber, drawing me in—toward my destiny. Visibility extends beyond 25 meters! My sight loses itself in the blue transparency that transitions into blackness. It's majestic, truly majestic. I keep a vigilant eye on my line, ensuring it doesn't snag in the narrow sections of the gallery. I leverage my optimal mental state to capture these envisioned magical moments—moments that are now mine. Another line splits on a sharp rock beneath me, and my computer alerts me: 400 minutes of decompression already! It feels too brief; I yearn to continue. It's a struggle to break free from the allure of unexplored depths. I hasten. Every passing second is crucial at these depths. I decide to secure my reel, leaving it to mark my terminus. A nod to Krzysztof Starnawski, another deep diver, who had abandoned a reel at the bottom of the magnificent Cetina spring in Croatia—an artifact I had retrieved during my initial dive there. I propel toward the distant surface. My ascent is swift. Eager to detach from the abyss and commence decompression. It's happening way too fast, and the cost will be high, though I'm unaware of that yet…
T+28 minutes - Junction!
Arriving early at the first stage at -130m, I commence following the deco stops. It's at -90m where Bruno, the support diver, finally joins me. Finally, I have access to all my measuring instruments. And there, I discover the incredible depth I've reached: -308m! Typically, during these deep dives, I initially monitor my condition, followed by the partial pressure of oxygen, the 'run time'—the diving time—and the expected duration of the stops. Depth becomes secondary... I don't fixate on it. If my body signals approval, I proceed. There wasn't any distress; it was the constraints of decompression time that compelled me to turn back.
T+40 minutes - I can't breathe anymore!
We're swimming towards the -80m level when I suddenly encounter extreme difficulty breathing—my rib cage feels constricted! My lungs seem blocked, my upper body trapped. Gas poisoning? Swiftly, I switch the rebreather tip, yet to no avail. It's not gas toxicity; the issue lies elsewhere. Faced with this unknown, fear lingers, but panic is unattainable. I must rely on my wisdom and experience... I try 'stomach breathing,' as in training. Labored. Like sipping through a straw. But even with limited ventilated volume, it suffices. Minutes tick by... Bruno remains by my side, watching over me for four hours. Worse still: a sharp pain grips my back. Alongside breathing difficulties, an oppressive sensation prevails—as if my suit is being crushed, the metal plate of my harness weighing tons. This ordeal extends for over an hour. It's only upon reaching the 30-meter mark that the grip eases, and I finally experience liberation. I inhale. I am alive. I remember... During the debrief with Bernard Gardette, director of deep dives and extreme environments at Comex—responsible for Théo Mavrostomos' legendary -701m dive—I learn that the visual illuminations I experienced are symptoms of HPNS. Tremors are more common. The spectrum of detrimental effects from neurological damage due to pressurized helium remains understudied. Reports mention vomiting issues. Thankfully, I escaped that underwater. These are irksome but reversible physical conditions, leaving the intellect unscathed. However, the respiratory oppression appears linked to a massive helium outgassing from my too rapid ascent. Circulating bubbles that I gradually eliminated from my lungs, yet symptoms of spinal cord and kidney injury persist. The spinal cord—a risk of permanent paralysis... Indeed, our computers are programmed to warn against rapid ascent. However, I've grown accustomed to my personal calculations and procedures, ignoring these warning bells, letting them ring out. Who's the boss here? I've grown accustomed to their persistent tunes, like a man at home ignoring his wife's shouts... Gardette confirms that we can ascend rapidly from -300m to -200m, but it's crucial to slow down before the first significant deco stop! Valuable information that I'll heed for my upcoming dive in the terminal well of the Mescla cave in the Var gorges.
T+120 minutes - The motionless journey
Franck joins us at a depth of 50m. It's time to jot down a message, a simple wet sheet of paper destined for other divers higher up and the surface. It reads: 'Fred -308m all is OK'... Many hours still separate me from the surface. I'm doubly confined: in the flooded gallery and by this physiological limit preventing me from directly ascending, risking a severe or even fatal decompression accident. I float, entering a 'degraded phase,' almost in a drowsy state. It's about aligning my physiology to its vital minimum, merging with water effortlessly. Listening to time stretch and dreaming of what lies beyond...
T+200 minutes - Leak…
As I approach the bottom of the exit shaft, daylight becomes visible from afar, urging me to scream. But at the -12m stop, a new alert emerges: a distinct sensation of fluid loss, from hip to foot. It feels as though I've urinated in my drysuit, an eerily realistic sensation sparking doubts. A slight movement reassures me—my leg functions properly, and I remain dry. However, the 'leak' persists, an unending 'bladder' sensation. Gardette later attributes this to 'skin sensations,' a decompression-related phenomenon sans gravity. 9m. The bell! I could conclude my decompression here, in dry comfort with legs in the water. Yet, I opt to forgo it. Changing the setup—a complete shift of environment, positioning, and potentially obstructed blood circulation—poses risks. So, I remain horizontal, weightless, in a daze, choosing optimal decompression. I float serenely, a weightless entity within my rocky vessel, content and almost at ease. Adjusting my heating: despite the relatively warm slightly brackish water at 18/19°C, the risk of cold remains due to immobility and stronger currents in this convergence point of the fountain's galleries. Life teems here! Curious eels navigate among my equipment, while silver mullets dance in the sun. At minus 6 meters, filamentous algae drape and twist like theater curtains, mingling with lignite roots and reed beds. Time for a snack—my Catalan country apricot compote bottles provide an unexpected energy boost. A realization strikes: dehydration likely plagues me, a negative factor for decompression. I'll need to remember to hydrate more during future attempts. Nearly 7 hours underwater, helium gradually dissipating from my body, the surface is tantalizingly close. I observe it, a reflective mirror above me. With humility, I reflect on this new milestone in exploration—a paradigm shift challenging established beliefs, a leap forward for the entire community. Our exploration endeavors always build upon past achievements. I think back to our pioneering elders, those who steadily dismantled psychological barriers. This marks a new frontier, a plank thrown into the swamp, paving the way for further progress. The great speleonauts all took this leap. It was time for me to do the same. I feel a sense of pride in these moments of pure beauty, in claiming a few dozen meters from the unknown, and in being able to recount this tale.
T+419 minutes - Surface!
I break the surface, lowering my mask and hood. There are splashes, silver droplets, laughter - sounds from the outside world; the smiles of friends. And the unmistakable scent of life...


Throughout all dives, Frederic has selected and tested a whole range of equipment from the best European manufacturers. As a propulsion system, Frederic chose Seacraft DPVs. Dual Ghost 2000 provides more than 10 hours of operation for 30 km of autonomy. Thanks to one of the unique Seacraft DPV features and EO output DPVs also serve as a big power bank for heating and lighting.

Faced with the configuration of the cave, Fred has chosen to separate the dual Seacraft GHOST scooters and use one as the primary scooter, and the other as a backup unit. Fredric and his team are currently using ENC3 navigation console data to understand the topography of the cave as precisely as possible, but also for medical decompression reports.




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