Free diving originally was an ancient method of harvesting sponges or pearls. It has now become an extreme sport. A free dive has no breathing assistance or tank but is dependent on the lung capacity of the diver. Spear fishermen, explorers and photographers free dive. So do sports competitors. Another term for it is apnea diving.
As science has been better able to monitor what happens in a diver’s body they have learned some interesting things. When a diver submerges, going progressively deeper, the air he is holding in his lungs becomes compressed. His lung tissue also becomes compressed. The rigid breast bone does not compress.At one time doctors and scientists believed that going beyond 115 feet deep could cause damage. Instead the diver’s blood fills that empty space by distending the blood vessels in that area. One variable scientists have been able to observe is that compression in divers varies with water temperature. These are observations that are actual measurements done in controlled circumstances of experienced breath holding divers.
The science of free diving relies on the mammalian dive reflex as well. What this means is that mammals have an automatic response when going deep under water holding their breath. This reflex redirects oxygen from extremities and toward the internal organs, especially the heart and brain. This keeps down potential serious damage to the diver.
Free diving can be fun for both beginner and expert, but it can be dangerous as well. None of the exercises and training systems is completely fool proof, and people have been injured or killed when they do not keep their body relaxed and their mind focused.
Generally beginners can train themselves to hold their breath about forty-five seconds, which would be to about a thirty foot depth. The top freediver recorded so far has reached an astonishing 700 foot depth. That was a record that could not be imagined less than a century ago.