World Record OC Dive by Pascal Bernabe

It has been years that I have waited for this moment: I am comfortably sitting on Denis Bignand’s U-Levante Diving Center’s boat. Under my fins that are already in the water, a 400-meter drop off! 

The Valinco waters are unexpectedly quiet! We had to push back this dive so many times because of the wind!

The realization of this dive had become an obsession, an idea stuck in my head.

At a short distance, on the coast, we can see Porto Polo. At my feet is the big buoy, attached to which is the 350-meter rope weighted with 50 kilos, plunging into the abyss… and waiting for me.

Too bad I still have this knot in my stomach, which remains despite the relaxation, quiet respiration and especially such good conditions. The team is active around me: Hubert, François, Tono, Christian, Sophie, Frank and Denis from U-Levante. I have already put on the 18-liter double set with another 7-liter for the dry suit, and very compact double wings.

(Click Images to Enlarge)

I have reduced the equipment to the strict minimum, in order to lower the risks of mistakes and confusion at the bottom.

Only the gas quantities have been “over rationed”. My fear has always been to ru ut of gas.

I enter the water and finish gearing up a little laboriously, but it is necessary. I don’t want to leave anything to chance. I try to keep concentrating in spite of the little last-minute problems.

I visualize the dive one more time, making sure I didn’t forget anything from the checklist, like you would go to space. Indeed, the ascent from the bottom will be even longer than a return journey from space. It really is for a trip to the unknown that I am preparing. In spite of the meticulous preparation, uncertainties remain, especially concerning my state of mind and body at the bottom, since only three scuba divers dove below 300 meters. 

With my movement slightly restricted by my six large tanks, I finally start my immersion. I break the surface of the sea, the barrier that separates the air, my friends and security from the depths of loneliness. At this moment, my stress should disappear… but it doesn’t. “Concentration” stops at -6 meters, but only for a moment,  I am in a hurry to be at the bottom. The descent commences, slow at first, then increasingly faster because of my weights.


At -70 meters, I hang my 18/50 tank, switch to the 6/72, and start gaining speed.

I break the minus one hundred meters level without paying much attention and continue gaining speed.

I pass the -150 meters tag. During my first gas mixture dives in 1993, that depth seemed quasi-inaccessible. But since 1996, between the underwater caves explorations and assisting dives with Pipin and Audrey Ferreras, I went back down between -150 and -174 meters about fifteen times, often with difficult conditions and tasks to accomplish (exploring, unwinding lines, filming, assisting…), which gave me a certain psychological comfort at this depth during the descent, but especially during the ascent at the decompression stops.

I just went to pass the -200 meters, for the third time since I have practiced deep diving.  The first time was in the huge underwater cave of Fontaine de Vaucluse in 1998, at more than – 250 meters! The second time was on the open sea off the Catalan coast, with the same team as for the record; I dove from the Majunga, François Brun’s boat, at -231 meters. But today, this is almost just a formality, since the objective is to go much deeper! 


Still no HPNS.

The rope slips quickly between my gloves. Too quickly! I need all my concentration to equalize,  to pass the tanks onto the big snap hook that secures me to the rope, to inflate my dry suit which is fortunately equipped with a big flow rate…

 I am approaching the last 20-liter tank, which is attached to the- 250 meter tag, although it is actually situated at -265 meters (because of the elasticity of the rope) with a chemical light stick, like for all cylinders at a depth.

Difficult moment: I abandon the 6/72 20-liter travel gas that I have been breathing since -70 meters, start breathing on the bottom mix, make the knot… too many things to do at the same time: the High Pressure Nervous Syndrome is well developed, in the form of light shivers, but especially with difficulty to concentrate.

Moreover, the travel gas tank that I was supposed to attach slips on the rope and gets away from me! My friends get it back a few minutes later without really understanding what is going on and not without a certain apprehension.  For me, of course, things are not getting better with the depth. I now feel comfortable with only four big tanks filled with bottom mix.

Strangely, passing -200 meters, I am shaking less than I was at the Fontaine du Vaucluse. I am not having any obvious visual disturbance (distance problem) either, except for an advanced “tunnel vision” effect: my visual field seems restrained, without much peripheral vision. My Apecks regulators and my Aqualung titan work wonderfully well. I hardly notice the -300 meter tag that really should grab my attention. A flasher is blinking, indicating the very deep zone. I reach the minus 320-meter tag (situated at more than -335 meters) when a big deflagration happens in my right ear, along with a sharp pain. My stress, that was gone since -70 meters, suddenly returns. At the time, I am sure that I had a big lesion on my eardrum. I quickly inflate my wings and begin the ascent. The pain in my ear doesn’t get worse. I avoid thinking about what is next, concentrating only on the ascent. 


At -265 meters, I happily reach the decompression tank for my first deep stop. Then the ascent starts again, slower (10 meters/min). Here again lies a big difference with the Fontaine du Vaucluse dive: THERE, the HPNS had touched me earlier, while leaving me later, around -70 meters. Today, I feel as though from -220 meters, few or no symptoms remain. At -215 meters, I make the second deep stop while I hang the second deco tank on. And it is even slower (5meters/min) that I reach the -165 meter deco stop and the next tank. My ear doesn’t hurt as much as I thought it would and I am in a familiar area. From -150 meters, the ascent becomes extremely slow (3 meters/min) especially with all of the tanks accumulating around me, on the rope and on my harness. 

When I get to -70 meters, there are nine 20-liter deco/travel tanks that I have to manage. 

At -65 meters, I get onto the second rope. There, I am happy to find François Brun, with whom I usually explore deep shipwrecks, one of them in particular, situated off the Catalan coast at -110 meters. Our last journey was a training exploration three weeks ago.  He’s using a Buddy Inspiration rebreather. He comes for an update and provides me with food and drink. I let him know about my pain in the ear and a light nausea. He helps me to get rid of four tanks by taking them and after spending a little while with me, goes to his own deco stops. 

Hubert Foucart relieves him at -50 meters. He is a follower of what he calls “baroque” diving: deep dives either in caves or on the open sea, down to -211 meters (not bad!), then assisting Pipin. He gives me a mix of water and vogalene in order to prevent nausea. Then, it is Denis’ its his turn to come to see me, also with his rebreather and brings me Sophie’ s good little purees and soups, in giant syringes. This salty food is a good alternative to condensed milk, sweet chestnut puree, marmalade, jelly and water already absorbed. Then he brings me a rebreather  that won’t work. Therefore, the rest of the ascent will be done in open circuit, but without any particular technical problem, in spite of the high percentages of helium.


From -30 meters, I start to feel more and more the effects of the strong surface swell. The pain in my ear increases and soon, each movement of the rope is going to become a nightmare. The decompression turns into torture. Moreover, at about -12 meters, the seasickness begins.  Dealing with the pain and the nausea begins to exhaust me. The end of the decompression is with Christian , Pierre, Lolo, Théo, Francis and his wife Sylviane who stay with me up to -3 meters and to the surface that I break after an 8 hours and 47 minutes dive.

The return to the surface that I dreamed of during the whole time of the decompression is brutal: I am shaken by the swell, which doesn’t help my seasickness. My friends help me get rid of my equipment, while I raise myself with difficulty on the Zodiac.

There, I am taken care of and quickly rushed to the shore by my old buddies Tono and Deit. Still exhausted, I keep breathing the oxygen for another half hour on the ground while rehydrating myself abundantly (water and water + Adiaril).

I should be happy. But I just feel a little bit more serene, and a little bit frustrated by the vertiginous, but too short descent… already a memory.

The GAME has worked today; my blood analysis wasn’t too bad.

However, I am already thinking about what could be improved.


Technical decompression: Several fundamental points:


Some initial 1 to 2 minute very deep deco stops were observed from -265 meters. And from that depth, the ascent speed decreased in order to avoid serious accidents of type 2: vestibular / neurological accidents whose symptoms may start deep in that type of dive, like the accident that John Bennett had after his -308 meters dive: dizziness, vomits from -66 meters and during the whole decompression (9h37min). It is important to note that the 30m/min ascent speed used to be typical!

This slow speed and those deep deco stops needed a big quantity of gas. That is why we used 20-liter tanks at -265 meters, -215 meters, -165 meters (8/62), -145 meters, -115 meters, (13/57), -95 meters, -80 meters (18/50), and also on a second line that was about 60 meters long: at -60 meters (20/50), -51 meters (25/50), -39 meters (25/50), -30 meters (38/33), -21 meters (50% O2), -15 meters (60% O2) and we also used two O2 sets of surface supply diving equipments at minus 6 meters. 

We will note the big quantity of helium used in the decompression mixes, easier to eliminate in the last deco stops. We avoided exceeding 30 % of nitrogen during the ascent up to -21 meters.

All those elements allowed me to have a relatively short decompression, compared to the 12 hours decompression that figures on my longest diving tables and is also Nuno Gomes’ decompression time, when he dove at -318 meters, 3 weeks earlier in Dahab, in the Red Sea.

Therefore, I opted to use those tables, because of the water conditions, the pains and the seasickness. I thought that staying longer would overexpose me to the risk of exhaustion.

Moreover, I could feel reassured knowing that in the 60s, Keller had only a 3 hour decompression (in a chamber) after a -300 meters dive! Plus, in 2004, Mark ELL YATT came out of a -313 meter dive in only 6h36. So I was using plenty of time. 


In order to limit narcosis deeper than -40/50 meters, we put in the gas mix some Helium whose proportion increases with the depth.  But this helium facilitates the cooling and especially the High Pressure Nervous Syndrome (HPNS).

This syndrome, basically, is aggravated by helium below -150/180 meters, and by the high speeds of descent specific to those dives.

About helium, many experiences in a chamber and a few ultra deep TEC dives showed that the presence of a narcotic gas, usually nitrogen, masked the effects of the HPNS: shaking of the extremities and then of the whole body, visual problems, difficulties to concentrate and diminution of performances.

A few years ago, I had thought about adding hydrogen but I gave up the idea because of the danger of manipulating this gas, and remaining uncertainty concerning the decompression and the effects of a fast compression.

But of course, the more nitrogen we add, the greater the risk of falling too much under the effect of narcosis… or even the risk of combining the effects of narcosis and HPNS!

Everything is therefore in the dosage: too much helium means too much HPNS; too much nitrogen means too much narcosis.

In the practice, while attempting relatively fast descents in the chamber (10 to 30 meters / min), it seems like doses of 13% to 18% nitrogen appreciably decreased the HPNS effects, without causing too much narcosis. On extremely deep TEC dives, the equivalent air depth of the divers at the bottom was situated between -70 and -100 meters. 

An equivalent air depth of -60 meters maximum seemed reasonable to me, associated with a partial oxygen pressure of 1.4 to 1.5 bars. 

That didn’t prevent a significant HPNS to affect me from -260 meters. However, that mix probably decreased its impact, and helped me avoid a dangerous narcosis.

Concerning the descent speeds, it seems, according to the experiences in the chamber, that descending one meter/minutes or even slower, notably increases the performances. 

But it doesn’t seem useful to reduce the speed from 30 to 40 m/min to 10 m/min. On the contrary, it is possible that the HPNS has more time to settle. On the other hand, it will considerably increase the already very long deco stops. 


The equipment:

It is just simply vital, on such an important dive that the equipment is simple, very solid and extremely high performing! It is entrusted with our lives more than anywhere else, and in the most extreme conditions!


One of the regulators that I used at the bottom was a Titan, which worked admirably. We often use it in cave diving, because the second stage is easy to disengage. Le Gend regulators (the top of the line) were settled on all decompression tanks, even the deep ones. Hubert and I had used Aqualung regulators during assisting dives with Pipin, between -140 and -170 meters. Hubert had also used them during a -211 meter dive. 


All bottom regulators were Apeks ATX 100, whose breathing capabilities are really impressive at -330 meters: with an Apeks it feels like breathing at only -20 meters! I used those regulators with total confidence, since they had successfully been used by a Norwegian at -225 meters, and even by John Bennett at -308 meters. It is also the most commonly used regulator amongst English Tec and cave divers in the worst conditions. 


AGA supplied ten Helium tanks and six oxygen tanks.


Fifty snap hooks specifically for each situation were used: locking snap hooks to secure the deco tanks as well as quick opening ones for delicate/fast operations. 

Petzl also supplied all the spelunking handles, which helped with manipulating ropes and bringing the tanks back up.


Tortec supplied the 7 to 18 liter tanks used at the bottom and during the decompression.


Béal supplied all the ropes: descent, decompression, shot line, etc. More than one kilometer in  total, as well as the cord and lines.


Partners in Corsica:

Diving Center U Levante, in Propriano

Without the help of Denis Bignand, who knows the bay like the back of his hand and all the best places, and who organized everything there, without his competence and his efficiency, we might still be looking for a site. He and his friendly instructors were a precious help to us, and I thank them.

Vigna Maggiore Camping, in Olmeto Beach

Jacques Bidani the friendly owner, welcomed us with opened arms and put us in two comfortable bungalows. He also entertained us with hearty local stories. 

The Maritime Agency Sorba, in Propriano, which really facilitated the Marseille-Corsica crossing. 

La Compagnie Méridionale de Navigation (the meridional navigation company)

Prima gas company, Barcarès Yatching, the Banque Populaire Toulouse Midi-Pyrénées (and the association of customers of this bank), Mr. Bordes and Mr. Mézergues and the Echelles Centaures, Mr. Vinsonneau and Mrs. Demoor, for the precious financial help. 

The Socex, in Castanet (31): Eric and Frank: oxygen and inspection.


The team:

16 people in total, divers or mariners.

From Toulouse and from Catalonia: they have followed this project (and other projects: shipwrecks, cave diving…) and have carried it on their shoulders since the beginning; everyone has his own specialty but continues to multitask. 

 Preparations, cancellations, and doubts have all been common since my -231m dive in 2003. Without these people or the patience of their families, none of this could have been done. I will never thank them enough for their kindness, efficiency and devotion. 

François Brun, well known shipwreck explorer.

Christian Deit, specialized in raiding, cave diver, canyon exploration, scuba diving. 

Hubert Foucart, cave diver and shipwreck explorer, with his passion for the deep dive…

Sophie Kerboeuf, highly skilled diver who cooked good little dishes for me.

Patrick Tonolini, cave diver and rebreather diver, who mixes everything with his Bauer-Purus.

And all the ones who were not able to come, amongst whom were Laurent, Paco…

In Propriano:

Denis Bignand and his instructors from U-Levante

Francis Machecourt from the CREPS of Ajaccio and his wife Sylvaine

Théo Laumonier

Laurent Grillot (Lolo)

Pierre Schiffer and Christian Gay-Capdeville from Aquasport Contois

Pascal Vieux and Jean-Louis Léandri, mariner from U-Levante.

Louis Lari from the Pilotine Santa Maria and his son Jean-Marie, pilote of the port.



To Henri Benedittini who brought us all of his help one more time.

To Bernard Gardette, the Comex scientific director, for all his valuable advices.

To the Professor Bourbon, from the Nervous System Functional laboratory (CHU Toulouse-Rangueil) for his formation in mental preparation.