Freediving, free-diving, free diving, breath-hold diving, or skin diving is a form of underwater diving that relies on divers' ability to hold their breath until resurfacing rather than on the use of a breathing apparatus such as scuba gear.
Examples of freediving activities are: traditional fishing techniques, competitive and non-competitive freediving, competitive and non-competitive spearfishing and freediving photography, synchronized swimming, underwater football, underwater rugby, underwater hockey, underwater target shooting and snorkeling. There are also a range of "competitive apnea" disciplines; in which competitors attempt to attain great depths, times, or distances on a single breath.
- 1 History
- 2 Freediving activities
- 2.1 Recreational hunting and gathering
- 2.2 Competitive breathhold watersports
- 3 Competitive apnea
- 4 Recreational
- 5 Physiology
- 6 Techniques
- 7 Training
- 8 Fiction and documentaries
- 9 See also
- 10 References
- 11 Further reading
- 12 External links
In ancient times freediving without the aid of mechanical devices was the only possibility, with the exception of the occasional use of reeds and leather breathing bladders. The divers faced the same problems as divers today, such as decompression sickness and blacking out during a breath hold. Freediving was practised in ancient cultures to gather food, harvest resources like sponge and pearl, reclaim sunken valuables, and to help aid military campaigns.
In Ancient Greece, both Plato and Homer mention the sponge as being used for bathing. The island of Kalymnos was a main centre of diving for sponges. By using weights (skandalopetra) of as much as 15 kilograms (33 lb) to speed the descent, breath-holding divers would descend to depths up to 30 metres (98 ft) to collect sponges. Harvesting of red coral was also done by divers.
The Mediterranean had large amounts of maritime trade. As a result of shipwrecks, particularly in the fierce winter storms, divers were often hired to salvage whatever they could from the seabed. Divers would swim down to the wreck and choose the most valuable pieces to salvage.
Divers were also used in warfare. Defenses against sea vessels were often created, such as underwater barricades - and hence divers were often used to scout out the sea bed when ships were approaching an enemy harbor. If barricades were found, it was divers who were used to disassemble them, if possible. During the Peloponnesian War, divers were used to get past enemy blockades to relay messages as well as supplies to allies or troops that were cut off, and in 332 BC, during Siege of Tyre, the city used divers to cut the anchor cables of Alexander's attacking ships.
In Japan, the Ama divers began to collect pearls about 2,000 years ago. For thousands of years, most seawater pearls were retrieved by divers working in the Indian Ocean, in areas such as the Persian Gulf, the Red Sea, and in the Gulf of Mannar (between Sri Lanka and India). A fragment of Isidore of Charax's Parthian itinerary was preserved in Athenaeus's 3rd-century Sophists at Dinner, recording freediving for pearls around an island in the Persian Gulf.
Pearl divers near the Philippines were also successful at harvesting large pearls, especially in the Sulu Archipelago. At times, the largest pearls belonged by law to the sultan, and selling them could result in the death penalty for the seller. Nonetheless many pearls made it out of the archipelago by stealth, ending up in the possession of the wealthiest families in Europe. Pearling was popular in Qatar, Bahrain, Japan, and India. The Gulf of Mexico was also known for pearling. Native Americans harvested freshwater pearls from lakes and rivers like the Ohio, Tennessee, and Mississippi, while others dived for marine pearls from the Caribbean and waters along the coasts of Central and South America.
Recreational hunting and gathering
Spearfishing is an ancient method of fishing that has been used throughout the world for millennia. Early civilizations were familiar with the custom of spearing fish from rivers and streams using sharpened sticks.
Today modern spearfishing makes use of elastic powered spearguns and slings, or compressed gas pneumatic powered spearguns, to strike the hunted fish. Specialised techniques and equipment have been developed for various types of aquatic environments and target fish. Spearfishing may be done using free-diving, snorkelling, or scuba diving techniques. Spearfishing while using scuba equipment is illegal in some countries. The use of mechanically powered spearguns is also outlawed in some countries and jurisdictions. Spearfishing is highly selective, normally uses no bait and has no by-catch.
Collection of shellfish
Competitive breathhold watersports
Aquathlon (also known as underwater wrestling) is an underwater sport where two competitors wearing masks and fins wrestle underwater in an attempt to remove a ribbon from each other's ankle band in order to win the bout. The "combat" takes place in a 5-metre (16 ft) square ring within a swimming pool, and is made up of three 30-second rounds, with a fourth round played in the event of a tie. The sport originated during the 1980s in the former USSR (now Russia) and was first played at international level in 1993. It was recognised by the Confédération Mondiale des Activités Subaquatiques (CMAS) in 2008.
Synchronized swimming is a hybrid form of swimming, dance, and gymnastics, consisting of swimmers (either solos, duets, trios, combos, or teams) performing a synchronised routine of elaborate moves in the water, accompanied by music. Synchronised swimming demands advanced water skills, and requires great strength, endurance, flexibility, grace, artistry and precise timing, as well as exceptional breath control when upside down underwater. During lifts swimmers are not allowed to touch the bottom.
Traditionally it was a women's sport, but following the addition of a new mixed-pair event, FINA World Aquatics competitions are open to men since the 16th 2015 championships in Kazan, and the other international and national competitions allow male competitors in every event. However, men are currently still barred from competing in the Olympics. Both USA Synchro and Synchro Canada allow men to compete with women. Most European countries also allow men to compete, and France even allows male only podiums, according to the number of participants. In the past decade more men are becoming involved in the sport and a global biannual competition called Men's Cup has been steadily growing.
Swimmers perform two routines for the judges, one technical and one free, as well as age group routines and figures. Synchronised swimming is both an individual and team sport. Swimmers compete individually during figures, and then as a team during the routine. Figures are made up of a combination of skills and positions that often require control, strength, and flexibility. Swimmers are ranked individually for this part of the competition. The routine involves teamwork and synchronization. It is choreographed to music and often has a theme. Synchronised swimming is governed internationally by FINA (Fédération Internationale de Natation).
Underwater Hockey, (also called Octopush (mainly in the United Kingdom)) is a globally played limited-contact sport in which two teams compete to manoeuvre a puck across the bottom of a swimming pool into the opposing team's goal by propelling it with a pusher. It originated in England in 1954 when Alan Blake, the founder of the newly formed Southsea Sub-Aqua Club, invented the game he called Octopush as a means of keeping the club's members interested and active over the cold winter months when open-water diving lost its appeal. Underwater Hockey is now played worldwide, with the Confédération Mondiale des Activités Subaquatiques, abbreviated CMAS, as the world governing body. The first Underwater Hockey World Championship was held in Canada in 1980 after a false start in 1979 brought about by international politics and apartheid.
Underwater football is a two-team underwater sport that shares common elements with underwater hockey and underwater rugby. As with both of those games, it is played in a swimming pool with snorkeling equipment (mask, snorkel, and fins). The goal of the game is to manoeuvre (by carrying and passing) a slightly negatively buoyant ball from one side of a pool to the other by players who are completely submerged underwater. Scoring is achieved by placing the ball (under control) in the gutter on the side of the pool. Variations include using a toy rubber torpedo as the ball, and weighing down buckets to rest on the bottom and serve as goals.
Underwater rugby is an underwater team sport. During a match two teams try to score a negatively buoyant ball (filled with saltwater) into the opponents’ goal at the bottom of a swimming pool. It originated from within the physical fitness training regime existing in German diving clubs during the early 1960s and has little in common with rugby football except for the name. It was recognised by the Confédération Mondiale des Activités Subaquatiques (CMAS) in 1978 and was first played as a world championship in 1980.
Underwater target shooting
Underwater target shooting is an underwater sport that tests a competitors’ ability to accurately use a speargun via a set of individual and team events conducted in a swimming pool using free diving or Apnea technique. The sport was developed in France during the early 1980s and is currently practised mainly in Europe. It is known as Tir sur cible subaquatique in French and as Tiro al Blanco Subacuático in Spanish.
Competitive freediving is currently governed by two world associations: AIDA International (International Association for Development of Apnea) and CMAS (Confédération Mondiale des Activités Subaquatiques – World Underwater Federation). Each organization has its own rules on recognizing a record attempt. These can be found on the website from the respective organizations.
Most types of competitive freediving have in common that it is an individual sport based on the best individual achievement. An exception to this rule is the bi-annual World Championship for Teams, held by AIDA, where the combined score of the team members makes up the team's total points. Another exception is the Skandalopetra diving by CMAS.
There are currently eleven recognized disciplines defined by AIDA and CMAS, and a dozen more that are only practiced locally. All disciplines can be practiced by both men and women and, while done outdoors, no differences in the environment between records are any longer recognized. The disciplines of AIDA can be done both in competition and as a record attempt, with the exception of Variable Weight and No limits, which are both solely for record attempts. For all AIDA depth disciplines, the depth the athlete will attempt is announced before the dive; this is accepted practice for both competition and record attempts.
|open water||pool||open water||pool|
|Speed-Endurance Apnoea||min. time||N||–||Speed-Endurance apnoea is an event where the athlete aims at covering a fixed distance at the minimum possible time. The event is swum in fractions of a pool length alternating apnoea swimming with passive recovery at the pool's ends.|
|STA – Static apnea||max. time||STA is timed breath holding and is usually attempted in a pool.|
|DYN – Dynamic apnea with fins||horizontal distance||–||For DYN the athlete can choose whether to use bi-fins or the monofin.|
|DNF – Dynamic apnea without fins||horizontal distance||–||This is underwater swimming in a pool for distance without any swimming aids like fins (AIDA).|
|The jump blue||horizontal distance||N||–||The jump blue also called "the cube" is a discipline in which an athlete has to descend and swim as far as possible in around a square of 15 meters side situated in a depth of 10 meters.|
|CWT – Constant weight apnea||depth||–||–||The athlete has to dive to the depth following a guide line that he or she is not allowed to actively use during the dive; only a single hold of the rope to stop the descent and start the ascent is allowed. The ‘Constant Weight’ (French: "poids constant") refers to the fact that the athlete is not allowed to drop any diving weights during the dive. Both bi-fins and monofin can be used during this discipline.|
|CNF – Constant weight apnea without fins||depth||–||–||CNF follows the identical rules as Constant Weight, except no swimming aids such as fins are allowed. This discipline is the youngest discipline within competitive freediving and is recognised by AIDA since 2003.|
|FIM – Free immersion apnea||depth||–||–||FIM is a discipline in which the athlete uses the vertical guiderope to pull him or herself down to depth and back to the surface without using ballast or fins. It is known for its ease compared with the Constant Weight disciplines, while the athlete is still not allowed to release weights.|
|VWT – Variable weight apnea||depth||–||–||VWT is a record discipline that uses a weighted sled for descent. Athletes return to the surface by pulling themselves up along a line or swimming with or without fins.|
|NLT – No-limits apnea||depth||–||N||NLT is a record discipline that allows the athlete to use any means of breath-hold diving to depth and return to the surface as long as a guideline is used to measure the distance. Most divers use a weighted sled to dive down and use an inflatable bag to return to the surface.|
|Skandalopetra||depth & min. time||N||–||The athlete dives with the help of a stone (usually a marble slab) attached to a rope. Skandalopetra is a team event: one athlete dives and one is waiting at the surface. When the first athlete reaches the desired depth, the second starts hauling him up.|
AIDA recognized world records
As of 9 September 2016, the AIDA recognized world records are:
|Discipline||Gender||Depth [m]||Distance [m]||Time||Name||Date||Place|
|Static apnea (STA)||Men||–||–||11 min 35 sec||Stéphane Mifsud (FRA)||2009-06-08||Hyères, Var, France|
|Women||–||–||9 min 02 sec||Natalia Molchanova (RUS)||2013-06-29||Belgrade, Serbia|
|Dynamic apnea with fins (DYN)||Men||–||300||–|| Mateusz Malina (POL) &
Giorgos Panagiotakis (GRE)
|Women||–||237||–||Natalia Molchanova (RUS)||2014-09-26||Sardinia, Italy|
|Dynamic apnea without fins (DNF)||Men||–||244||–||Mateusz Malina (POL)||2016-07-02||Turku, Finland|
|Women||–||185||–||Magdalena Solich (POL)||2016-07-02||Turku, Finland|
|Constant weight apnea (CWT)||Men||128||–||–||Alexey Molchanov (RUS)||2013-09-19||Kalamata, Greece|
|Women||101||–||–||Natalia Molchanova (RUS)||2011-09-22||Kalamata, Greece|
|Constant weight apnea without fins (CNF)||Men||102||–||–||William Trubridge (NZL)||2016-07-20||Dean's Blue Hole, Long Island Bahamas|
|Women||72||–||–||Sayuri Kinoshita (JPN)||2016-04-26||Dean's Blue Hole, Long Island Bahamas|
|Free immersion apnea (FIM)||Men||124||–||–||William Trubridge (NZL)||2016-05-02||Dean's Blue Hole, Long Island Bahamas|
|Women||92||–||–||Jeanine Grasmeijer (NED)||2016-09-06||Kralendijk, Bonaire|
|Variable weight apnea (VWT)||Men||146||–||–||Stavros Kastrinakis (GRE)||2015-11-01||Kalamata, Greece|
|Women||130||–||–||Nanja van den Broek (NED)||2015-10-18||Sharm el-Sheikh, Egypt|
|No-limits apnea (NLT)||Men||214||–||–||Herbert Nitsch (AUT)||2007-06-14||Spetses, Greece|
|Women||160||–||–||Tanya Streeter (USA)||2002-08-17||Turks and Caicos|
CMAS recognized world records
As of October 2016, the CMAS recognized world records are:
|Discipline||Gender||Depth [m]||Distance [m]||Time||Name/Country||Date||Place|
|–||Speed 100 m apnea with fins||Men||–||–||00:31.925||Max Poschart (DEU)||2016-06-09||Lignano, Italy|
|Women||–||–||00:37.235||Alina Markovtcova (RUS)||2016-06-09||Lignano, Italy|
|STA||Static apnea||Men||–||–||10:39.000||Branco Petrovic (SRB)||2015-07-30||Mulhouse, France|
|Women||–||–||08:33.230||Gabriela Grézlová (CZE)||2015-07-28||Mulhouse, France|
|DYN||Dynamic apnea with fins||(50 m pool)||Men||–||300.00||–||Arthur Guérin-Boëri (FRA)||2016-06-11||Lignano, Italy|
|Women||–||250.00||–||Alessia Zecchini (ITA)||2016-06-11||Lignano, Italy|
|DNF||Dynamic apnea without fins||(50 m pool)||Men||–||189.65||–||Olivier Elu (FRA)||2016-06-08||Lignano, Italy|
|Women||–||171.22||–||Alessia Zecchini (ITA)||2016-06-08||Lignano, Italy|
|(25 m pool)||Men||–||200||–||Arthur Guérin-Boëri (FRA)||2013-08-09||Kazan, Russia|
|Women||–||175||–||Katarina Zubčić (HRV)||2013-11-15||Zagreb, Croatia|
|–||Jump blue apnea with fins||(at sea)||Men||–||201.61||–||Arthur Guérin-Boëri (FRA)||2015-10-09||Ischia, Italy|
|Women||–||190.48||–||Alessia Zecchini (ITA)||2015-10-09||Ischia, Italy|
|CWT||Constant weight with fins||(at sea)||Men||110||–||–||Goran Čolak (HRV)||2015-10-06||Ischia, Italy|
|Women||93||–||–||Alessia Zecchini (ITA)||2015-10-06||Ischia, Italy|
|(fresh water)||Men||75||–||–||Michele Tomasi (ITA)||2013-09-14||Trento, Italy|
|Women||57||–||–||Tanya Streeter (USA)||1998-12-28||Ocala, Fl, USA|
|CNF||Constant Weight without fins||(at sea)||Men||78||–||–||Michal Rišian (CZE)||2016-10-08||Kaş, Turkey|
|Women||60||–||–||Alena Konečna (CZE)||2016-10-08||Kaş, Turkey|
|(fresh water)||Men||65||–||–||Michal Rišian (CZE)||2016-07-10||Weyregg, Austria|
|FIM||Free immersion apnea||(at sea)||Men||81||–||–||Devrim Cenk Ulusoy (TUR)||2012-09-25||Kaş, Turkey|
|Women||72||–||–||Şahika Ercümen (TUR)||2014-07-24||Kaş, Turkey|
|VWT||Variable weight apnea with fins||(at sea)||Men||131||–||–||Homar Leuci (ITA)||2012-09-11||Soverato, Italy|
|–||Variable weight apnea without fins||(at sea)||Men||81||–||–||Devrim Cenk Ulusoy (TUR)||2012-09-26||Kaş, Turkey|
|Women||91||–||–||Şahika Ercümen (TUR)||2014-07-23||Kaş, Turkey|
Freediving is also a recreational activity, celebrated as a relaxing, liberating and unique experience significantly different from scuba diving. The advantages freediving has over scuba diving are:
- less equipment to wear
- greater mobility and speed
- lower diving costs
- shorter preparation time
- no decompression time for deep dives, (although it is possible to get decompression sickness, or taravana, from repetitive deep free-diving with short surface intervals).
- greater visibility (in upwards direction) due to a lack of exhaled air bubbles
- no distracting sounds like regulator breathing (also possible when using a rebreather)
- greater time in the water since air tank refills are not needed
Experienced freedivers can often go as deep as scuba divers, and sometimes deeper. Recreational scuba diving is generally limited by diver certification to a maximum of 40 meters, for reasons of safety. Recreational divers who dive to deeper depths are generally expected by the certification agencies to have technical diver training, while freediving is only limited by the divers ability and willingness to accept the risks. Recreational freediving is practiced by many people ranging from the average snorkeler to the professional freediver. Recreational freediving is also frequently practiced in freshwater springs due to excellent visibility.
Freediving into spring caverns and caves is very different from diving in the ocean or other open water (water with an unobstructed vertical access to the surface). Even though every spring cave is unique, these are the general differences:
- A dive light is usually required.
- The freediver must usually swim laterally to exit the cave before ascending to the surface.
- The freediver may also pull on large rocks or the cave structure to enter/exit the cave.
- The freediver must avoid stirring up silt so that visibility is not lost.
- To conserve energy/oxygen, if possible, the current should be avoided while entering the cave, but it can be used to help exit the cave.
- If the freediver is penetrating the cave so far that surface light is lost, proper navigation and passage recognition is vital along with a backup dive light.
- If large air pockets are found inside the cave, they are usually unsafe to breathe from.
- Usually a monofin is impractical to use due to limited space.
- Some cave passages are so small that shorter fins are better to use than long freediving fins.
- The risk of drowning when freediving in an overhead environment is significantly increased. Loss of light, silting, losing the guideline in the dark and any other form of disorientation is likely to have fatal consequences.
The time that a freediver can spend underwater on a single excursion is severely restricted in comparison with scuba, and a considerably greater level of fitness is required for longer breathhold times. A scuba diver generally has sufficient time to recover from a minor disorientating incident in a cave, as there is sufficient breathing gas to perform the recovery procedures. This is not available to the freediver, who has only the oxygen still available in their system.
The human body has several oxygen-conserving adaptations that manifest under diving conditions as part of the mammalian diving reflex. The adaptations include:
- Reflex bradycardia: Significant drop in heart rate.
- Blood-shift: Blood flow and volume is redistributed towards vital organs by means of a reflex vasoconstriction. Blood vessels distend and become engorged, which in the case of the pulmonary capillaries assists with pressure compensation that comes with increasing diving depth, and without which a largely air-filled chest cavity would simply collapse for lack of compliance.
- Body-cooling: peripheral vasoconstriction results in cooling of peripheral tissue beds, which lower their oxygen demand in a thermodynamic manner. In addition, Murat et al. (2013) recently discovered that breath-holding results in prompt and substantial brain cooling, just like in diving birds and seals. (Dry) breath-holds result in cooling on the order of about 1 °C/minute, but this is likely to be greater with cold water submersion, in proportion to the magnitude and promptness of the dive response.
- Splenic contraction: Releasing red blood cells carrying oxygen.
Breath-holding ability and, hence dive performance, is a function of on-board oxygen stores, scope for metabolic rate reduction, efficient oxygen utilization, and hypoxia tolerance. Various athletes attempt to accomplish this in various ways. By and large most divers rely on increasing fitness by increasing lung capacity. Some use `packing´ which increases lung volume beyond normal total lung capacity. Needless to say, simple breath-holding is highly effective for increasing lung capacity. In addition, training is allocated to enhance blood and muscle oxygen stores, to a limited extent. A substantial proportion of performance is the result of metabolic suppression and redistribution of blood oxygen stores, the so-called dive response.
Training for freediving can take many forms and be performed on land.
One example is the apnea walk. This consists of a preparation "breathe-up", followed by a short (typically 1 minute) breath hold taken at rest. Without breaking the hold, the participant then initiates a walk for as far as they can, until it becomes necessary to breathe again. Athletes can do close to 400 meters in training this way.
This form of training is good for accustoming muscles to work under anaerobic conditions, and for tolerance to CO2 build-up in the circulation. It is also easy to gauge progress, as increasing distance can be measured.
Before competition attempt, freedivers perform preparation sequence, which usually consists of physical stretching, mental exercise and breath exercise. It may include sequention of variable length static apnea and special purging deep breaths. Result of preparation sequence is slower metabolism, lower heart rate and breath rate, lower level of CO2 in bloodstream and overall mental equilibrium. Failing ordinary warning signals or crossing mental barrier by strong will may lead to shallow water blackout or deep water blackout. Trained freedivers are well aware of this and will only dive under strict and first aid competent supervision. However this does not eliminate the risk of deep or shallow water blackout. All safe freedivers have a 'buddy' who accompanies them, observing from within the water at the surface. Due to the nature of the sport, any practice of freediving must include strict adherence to safety measures as an integral part of the activity, and all participants must also be adept in rescue and resuscitation. Without proper training and supervision, freediving/apnea/breath-hold diving is extremely dangerous.[clarification needed]: The death of Nicholas Mevoli, a diver from New York, highlights the dangers of freediving. He died on 17 November 2013 after completing a dive to a depth of 72 metres.
Fiction and documentaries
- In the film Mission Impossible - Rogue Nation, Tom Cruise plays super spy Ethan Hunt fighting the forces of evil, and goes freediving in a scene to expose the villains.
- The Pearl by John Steinbeck (1947) is a novel about a poor pearl diver, Kino, who finds the 'Pearl of Heaven', which is exceptionally valuable, changing his life for ever. The novel explores themes of man's nature as well as greed and evil.
- In South Sea Adventure (1952) by Willard Price the Hunt brothers, marooned on a coral island, use free diving to collect both pearls and fresh water.
- In Ian Fleming's (1964) James Bond novel You Only Live Twice, the character Kissy Suzuki is an ama diver. This connection was also mentioned in the film version.
- Man from Atlantis was a 1970s TV series which featured a superhero with the ability to breathe underwater and freedive in his own special way.
- The Big Blue (1988) is a romantic film about two world-class freedivers, a heavily fictionalized depiction of the rivalry of freedivers Jacques Mayol and Enzo Maiorca.
- Ocean Men (2001) is a documentary film about the art and science of freediving, featuring two of its most outstanding exponents: Francisco "Pipín" Ferreras and Umberto Pelizzari.
- In the movie Phoenix Blue (2001), protagonist Rick is a musician who freedives competitively.
- The children's novel The Dolphins of Laurentum by Caroline Lawrence (2003), which takes place in ancient Rome, describes the applications of freediving (sponge and pearl diving), and its hazards, as one of the principal characters, as well as the main antagonist, try to beat each other to a sunken treasure.
- The Freediver (2004) is a film about a talented female freediver who is discovered and brought to an island, where she is trained by an ambitious scientist to break a freediving world record currently held by an American woman.
- In the film Into the Blue (2005) starring Jessica Alba, a group of divers find themselves in deep trouble with a drug lord after they come upon the illicit cargo of a sunken airplane in the Caribbean. Jessica Alba is an accomplished freediver, and did much of the underwater work; some other stunts were performed by Mehgan Heaney-Grier.
- In Greg Iles' novel Blood Memory (2005), the main character Cat Ferry is an odontologist and a freediver.
- H2O: Just Add Water Series 3 added a freediver (Will Benjamin played by Luke Mitchell) as a regular. Freediving is featured in some episodes.
- The Greater Meaning of Water (2010) is an independent film about competitive constant weight freediving, focusing on the 'zen' of freediving.
- In the Canadian television series Corner Gas, the character Karen Pelly (Tara Spencer-Nairn) competed in static apnea, ranking fifth in Canada with a personal best of over six minutes.
- In the American television series Baywatch episode "The Chamber" (Session 2, Episode 17), the character Mitch Buchannon rescues a diver trapped 90 feet below the ocean surface, but almost dies while suffering the effects of decompression sickness; decompression sickness is highly improbable following freediving exposure to this depth.
- Dimitri Rebikoff,(1955) Free Diving, Sidgwick & Jackson
- David M. Owen,(1955)A Manual for Free-Divers Using Compressed Air, Pergamon
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- Sandra Hendrikse; André Merks (12 May 2009). "Diving the Skafandro suit". Diving Heritage. Retrieved 2009-10-16.
- Galili, Ehud; Rosen, Baruch (2008). "Ancient Remotely-Operated Instruments Recovered Under Water off the Israeli Coast". International Journal of Nautical Archaeology. Nautical Archaeology Society. 37 (2): 283–94. doi:10.1111/j.1095-9270.2008.00187.x.
- Frost, FJ (1968). "Scyllias: Diving in Antiquity". Greece and Rome (Second Series). Cambridge University Press. 15 (2): 180–5. doi:10.1017/S0017383500017435.
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- Rahn, H.; Yokoyama, T. (1965). Physiology of Breath-Hold Diving and the Ama of Japan. United States: National Academy of Sciences – National Research Council. p. 369. ISBN 0-309-01341-0. Retrieved 2009-04-16.
- De Silva, K. M. (1995). Volume 2 of History of Ceylon, History of Ceylon: History of Sri Lanka. Peradeniya: Ceylon University Press. p. 56. ISBN 955-589-004-8.
- Ἰσίδωρος Χαρακηνός [Isidore of Charax]. Τὸ τῆς Παρθίας Περιηγητικόν [Tò tēs Parthías Periēgētikón, A Journey around Parthia]. c. 1st century AD (Ancient Greek) in Ἀθήναιος [Athenaeus]. Δειπνοσοφισταί [Deipnosophistaí, Sophists at Dinner], Book III, 93E. c. 3rd century (Ancient Greek) Trans. Charles Burton Gulick as Athenaeus, Vol. I, p. 403. Harvard University Press (Cambridge), 1927. Accessed 13 Aug 2014.
- Streeter's Pearls and pearling life dedicates a chapter to the Sooloo islands. Streeter was one of the leading and most influential English jewelers in the 19th century and outfitted his own Schoener the Shree-Pas-Sair which he sailed as well and on which he himself went pearl fishing in 1880. (See for illustration of divers on Schoener Pearl fishers obtaining the world's best pearls. Streeter furthermore led a consortium to compete with Baron Rothschild to lease Ruby mines in Burma.
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- "Where is it Played". underwaterfootball.com. Retrieved 7 November 2014.
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- "GO AHEAD, VENT YOUR SPLEEN!", Sarah Milton, 2004, Journal of Experimental Biology
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- Fitz-Clarke, JR (2006). "Adverse events in competitive breath-hold diving.". Undersea Hyperb Med. 33 (1): 55–62. PMID 16602257. Retrieved 2013-10-06.
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- DeeperBlue.com (2016) The Beginners Guide to Freediving, published by DeeperBlue.com
- Callagy, Feargus (2012) A Beginners Guide to Freediving, e-book published by DeeperBlue.com
- Donald, Ian (2013) Underwater foraging – Freediving for food, Createspace publishing, USA. ISBN 978-1484904596
- Farrell, Emma (2006) One Breath: A Reflection on Freediving, photographs by Frederic Buyle, Pynto Ltd., Hatherley, UK: ISBN 0-9542315-2-X
- Pelizzari, Umberto & Tovaglieri, Stefano (2001) Manual of Freediving: Underwater on a single breath, English translation 2004 by Idelson-Gnocchi Ltd., Reddick, FL: ISBN 1928649270
- Severinsen, Stig A. (2010) Breathology: The Art of Conscious Breathing, Idelson-Gnocchi Ltd., Reddick, FL: ISBN 978-1928649342
- James Nestor (2015) "Deep: Freediving, Renegade Science, and What the Ocean Tells Us About Ourselves", Eamon Dolan/Mariner Books New York, NY: ISBN 978-0544484078
- AIDA International
- Collaborative cartography of freediving spots/Cartographie collaborative des spots apnée (French)
- DeeperBlue website
- The Beginners Guide to Freediving - published by DeeperBlue.com
- FreedivingCourses.com - a way to find Freediving instructors and dive centers around the world
- DiveWise.Org - non profit organization dedicated to freediving education and safety
- Explore Freediving - Freediving and Snorkeling events and instructor directory
- Freediving Spots
- Borgosub.fr French association to promote Wreck freediving