What happens to the body when you go deep? This infographic explains some of the physiological changes that the body goes through on a dive. But one thing it can't explain – and that's the feeling.
Says Will Trubridge: “I love freediving because it's an opportunity to escape from gravity, sound, light (if you go deep) and even the sensation of time passing. A deep freedive can be like a dream, in that all the rules of reality seem changed.”
Dive in below to discover more about the sport, the physiology and the different disciplines...
infographic created by: zooom.at/Adi Sumic
The Dive Reflex
It is often said that humans are perfectly adapted for diving underwater thanks to the 'mammalian or dive reflex' – something we share with other aquatic mammals such as whales and dolphins. The main feature of this is the way the heart rate automatically slows once the face is submerged in water to reduce oxygen consumption.
The dive reflex kicks in again after approximately 25 m: the heart rate slows by as much as 50% and vasoconstriction takes place. This is where warm blood retreats from the body's extremities to protect core organs.
At this depth most divers can stop swimming. “Here I have lost enough buoyancy from lung shrinkage under pressure that I can stop swimming and freefall for the rest of the descent,” says Will.
There are three main depth disciplines in competition freediving:
Constant Weight No Fins (CNF): The freediver descends and ascends without any assistance (only using arms and legs without fins).
Constant Weight with Fins (CWT): The freediver descends and ascends using fins/monofin and the use of arms.
Free Immersion (FIM): The freediver dives without the use of fins/monofin, but pulls a rope during descent and ascent.
Says Trubridge: “CNF and CWT are the two most popular disciplines. CWT gives the deepest performances, while CNF is seen as the purest expression of human aquatic potential. FIM is more of a relaxed discipline, but there are definitely some very serious practitioners there as well!”