The risk and reward of freediving

21 April 2016

Freediving refers to competitive breath-hold diving and is also known as competitive apnoea.

The oldest evidence of freediving has been found about 10,000 years ago on the coast of the Baltic Sea. This ancient civilisation has been named “The Clam Eaters” because the remains of clams and shellfish have been found indicating these people obtained their food from the ocean floor by means of freediving.

Pearls that can only have been retrieved from the bottom of the ocean were used in jewellery in Egypt around 5,000 year ago. Archaeological findings and both Greek and Latin literature indicate that Mediterranean cultures regularly practised freediving.

As long as 2,500 years ago free divers were used during warfare to get past enemy ship blockades to relay messages and provide supplies to troops that were cut off. The divers were also used to sabotage boats by drilling holes in enemy hulls.

That’s the short history lesson over – now let’s talk about the dive. The following is based on a world record diver by the name of Guillaume Néry who has reached a depth of 123 metres.

The dive is essentially a journey between two breaths – a journey that pushes the limits of human possibility while taking one into the unknown. Physiological and mental challenges ensure that the risk is extremely high, but due to the nature of freediving, apart from the lucky few, not many people will ever experience the final reward. A weighted rope with distance markers is beside you and this rope can only be touched twice – once when you leave the surface and again when reaching the bottom.

The first step is the last breath which is slow and deep and is aided by a technique called the carp which allows a couple of extra litres of air to be stored in the lungs by means of compression. The average lung capacity of an adult human male is around 6 litres, but with this technique a free diver can pack up to 10 litres of air in their lungs.

The diving reflex occurs as soon as the descent starts – this is a mammalian reflex that selectively shuts down certain body functions to conserve energy. This is a survival technique that is triggered when the face makes contact with cold water. The heart rate will drop from about 70 to around 40 beats per minute and the blood flow will leave the body’s extremities to provide blood to the 3 most important organs being the heart, lungs and brain. It’s nature’s way of giving you a little help at the beginning of your journey and is a natural mechanism for marine mammals.

Not far from the surface pressure starts to squeeze the lungs and seeing that the air in the lungs is what causes us to float the deeper we go the more the lung pressure increases. As the air is compressed it actually makes it easier to descend and at around 40 metres you can stop swimming as the body is now heavy enough to descend on its own. This phase of the dive is called the free fall and is widely enjoyed as the best part of a dive as the body is being pulled downwards within any effort being made. Divers can descend from the 40 metre mark to over 100 metres without making any movement.

At around 60 metres another body response kicks in called blood shift when the lungs’ blood vessels expand resulting in a reduction of the residual lung volume. This increases the maximum possible depth of the dive. An average untrained diver will probably experience this effect at around 30 metres. This hardens the walls of the lungs and essentially stops the ribcage from collapsing and crushing the lungs.

Around 80 metres the diver really starts to feel the pressure and the feeling of suffocation. Their mental training kicks in as the diver must accept and allow the body to be crushed by pressure as any normal physiological resistance will result in tearing of the lungs. Once this mental barrier is overcome the lungs then start to relax as the mind accepts the level of pressure.

100 metres is a magical number in free diving – statistics estimate only 1% of free divers can reach 100 metres and only 0.25% can dive beyond 110 metres. Only about 50% of free divers can reach 45 metres so this truly is an exclusive group of people who take the risk and reach over 100 metres. In the 1970’s doctors predicted that 100 metres was the absolute maximum and below that the body would implode. It always takes one person to push the limits and in 1976 Jacques Mayol became the first person to free dive to 100 metres thus debunking the medical community beliefs and creating the possibilities for much deeper dives.

The end of the dive has been reached at a depth of 123 metres – the diver is alone, almost no light, extremely cold and the pressure is now approximately 12 times stronger than on the surface. On the positive side it is very quiet, tension has been released, no urge to breathe and a feeling of well-being. Look in any direction and it’s just the deep blue ocean – the same view all around you.

Now for the return to the surface. It takes a great physical effort to grasp the rope and reverse direction as now you are fighting the force that propelled you down and have to swim twice as hard on the way back up. Narcosis now occurs in which the body experiences a form of intoxication when nitrogen dissolves in the blood causing confusion and drowsiness. Again, mental strength is needed to accept and manage this feeling. To make things worse at a depth of around 70 metres you now have a desire to breathe and overcome the natural reaction to panic and look for the surface. You should never look towards the surface or even imagine being on the surface – stay in the present and focus on the rope that leads you back to the surface.

Focussing on the rope, fight the urge to panic and do not look up and soon you reach 30 metres and receive some salvation in the form of the safety divers. These divers are escorts over the last few metres of the ascent where potential problems could arise. At around 20 metres the lungs start to expand again and return to their normal volume thus providing the now familiar buoyancy that pushes you to the surface. A few metres below the surface, almost unbelievably the diver breathes out the remaining air and as the surface is broken the first deep breath is taken with air flooding into the lungs. Some divers describe these initial breaths as a feeling of being reborn. Many divers experience the trauma of surfacing as the transition from darkness to light, silence to noise and the sudden feeling of fresh air on the skin.

This transition can take a few seconds and if in a competitive dive the judges need to see that the diver shows the universal okay sign, is in good physical condition and is aware of the surroundings. If the judges are happy a white card is shown and the celebrations can begin.

With thanks to Guillaume Néry for telling his story of a sport that very few people will see.

Author – Warrick Asher

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