• Depths of 0-100 feet.
• Many repetitive dives between 30 sec to 2 minutes.
• Freedivers stay within their own limits
• Freedivers rely on themselves and their buddy for safety.
• Freedivers interact with marine life, explore wrecks and structures, and explore terrain.
• Competitive freedivers test themselves for time, depth and distance underwater.
• Performances are more than double recreational time, depth and distance.
• Extensive safety arrangements are made, including safety SCUBA and freedivers.
• Freedivers test their limits.
• Freedivers at a higher risk of samba or blackout.
A. Static Apnea (STA) This discipline consist of holding your breath for as long as possible while staying motionless. It sets high demands for the competitor's concentration ability.
B. Dynamic Apnea without Fins (DNF)
A variation of the above, where the longest possible distance is achieved without the use of fins.
C. Dynamic Apnea with Fins (DYF)
This consist of the athlete making use of fins to swim the longest possible distance under water.
D. Free Immersion Apnea (FIM)
This discipline allows the competitor to pull along the measuring rope to his/her depth and back again.
E. Constant Weight Apnea (CWA)
This discipline is considered by insiders to be the original freediving discipline. The athlete makes use of traditional ABC-equipment to reach his/her depth. The discipline sets the highest demands to the freediver's mental power, physique and technique.
F. Constant Weight Apnea without Fins (CWAF)
This discipline consists of swimming down and up along the rope as in classic constant weight, but without the use of fins and using breast strokes. This discipline has been called 'the true human aquatic potential'.
G. Variable Weight Apnea (VWT)
In this discipline the diver makes use of a specially designed sled running along the measuring rope to achieve his/her depth. Historically, the sled has evolved from a simple weight attached to a noose, till today's highly sophisticated, hydrodynamic sled leading the diver downward with high speed. The freediver traditionally makes use of the measuring rope to pull back to the surface.
H. No-Limits Apnea (NLT)
This has traditionally been the discipline to reach the deepest of all disciplines today. It is a further development of variable weight, where the athlete apart from the sled traditionally makes use of an inflatable balloon to return to the surface.
3. Weight belt or neckweight
穿着weight belt就不需要用太多力气skin dive到水里了。
Some of you may experience abdomibal contractions at some point during breathold. This is a natural reflex caused by the urge to breath (usually due to elevated CO² levels). Contractions don't mean you immediatly have to surface and breathe, you can do a while longer.
Samba or LMC (Loss of Motor Control)
You get a LMC when your oxygen level is too low. When you have a samba you shake (minor to heavily) like an epileptic stroke.
There are different types of black-outs, the Shallow Water Black-out (SWB) and the Pool Black-out.
这就是为什么下水之前不可以hyperventilate了。Hyperventilate之后，oxygen level会去到很高，潜到水里不会有不快的感觉。当CO2 level去到很高的时候，你还是不会觉得累的（因为你做了hyperventilation）。Black-out就会突然发生。
Shallow-water blackout is a sudden unconsciousness; can occur while practicing depth disciplines. The lungs expand (due to a pressure differential on ascent) and "suck" oxygen from the blood.
Pool Black-out You get a pool black-out when your oxygen level is way too low because of a long breath hold.
Laryngospasm Laryngospasm is a protective reflex that protects the airway by closing off the vocal cords preventing water from entering the lungs. This is usually stimulated when water hits the back of the throat. One should do two rescue breaths to break the spasm and the airway should open and spontaneous breathing begins. If it doesnt then continue rescue breathing at one breath every five seconds.
The Buddy system
The buddy system is a system for Freedivers to dive safely, never dive without a buddy!! Your buddy should know all safety procedures (see below). You can find buddies on this forum in the find a buddy/ places to dive forum. A lifeguard at a pool is never good enough, even if you ask them to keep an eye on you, people have drowned even with a lifeguard keeping an eye them.
Safety Procedures The basic safety procedure is one diver down the other on the surface keeping an eye on the diver.
In static the one on the surface keeps not only the time but also taps the diver on the shoulder after a period of time, to check if the diver is still fully conscious. The diver should respond by giving an OK signal or by sticking the index finger up. If the diver does not respond to the tap turn him around immediately, keep his airways above the water and take his mask off, if the diver has lost consciousness tell him to breath or call his name and blow him gently in the face (mouth and nose) and he should wake up, never slap or shout at the diver! It is very useful to know CPR in a worst case scenario, although it is very, very rare that CPR is used to recover the diver.
In Dynamic the buddy uses a snorkel and swims along with the diver, if the diver suddenly blows out his air, pull him up to the surface, if the diver stops swimming, pull him up to the surface, after pulling the diver up to the surface use the same procedure used in static.
In Constant Weight and Free Immersion the buddy stays on the surface and meets the Freediver somewhere on ascent, never dive too deep and gain confidence in your current depth before increasing that depth. Increase depth gradually!