Freediver with monofin, ascending

Freediving, free-diving, free 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.

(Historically, the term free diving was also used to refer to scuba diving, due to the freedom of movement compared to surface supplied diving.)[1][2][3]


Natural sponges have been harvested by freedivers near the Greek island of Kalymnos since at least the time of Plato.

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.[4] 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.[5] 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.[6] 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.[7] 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,[8] 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.[9][10] 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).[11] 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.[12]

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.[13] 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.

Freediving activities

Recreational hunting and gathering


a man with a speargun is freediving over coral
Spear fisherman in Hawaii

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.

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.[14][15][16][17]

Synchronised swimming

A member of the Japanese team is thrown up in the air by other members under the water during the team's free routine at the 2013 French Open.

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

Two players compete for the puck in underwater hockey

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.[18] Underwater Hockey is now played worldwide, with the Confédération Mondiale des Activités Subaquatiques, abbreviated CMAS, as the world governing body.[19] 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

US Navy Students playing underwater football

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.

It is played in the Canadian provinces of Alberta, Manitoba, Newfoundland and Labrador and Saskatchewan.[20]

Underwater rugby

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 Apnoea 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 apnea

Monofin freediver

Competitive freediving is currently governed by two world associations: AIDA International (International Association for Development of Apnea)[21] 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.

discipline measurement AIDA[22] CMAS[23] description
open water pool open water pool
Speed-Endurance Apnoea min. time Red X Green tick 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.
STAStatic apnea max. time Green tick Green tick Green tick Green tick STA is timed breath holding and is usually attempted in a pool.
DYNDynamic apnea with fins horizontal distance Green tick Green tick Green tick For DYN the athlete can choose whether to use bi-fins or the monofin.
DNFDynamic apnea without fins horizontal distance Green tick Green tick Green tick This is underwater swimming in a pool for distance without any swimming aids like fins (AIDA).
The jump blue horizontal distance Red X Green tick 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.
CWTConstant weight apnea depth Green tick Green tick 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.
CNFConstant weight apnea without fins depth Green tick Green tick 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.
FIMFree immersion apnea depth Green tick Green tick 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.
VWTVariable weight apnea depth Green tick Green tick 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.
NLTNo-limits apnea depth Green tick Red X 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 Red X Green tick 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.
Herbert Nitsch, World Record Holder Freediver

AIDA recognized world records

As of 9 September 2016, the AIDA recognized world records are:[24]

Discipline Gender Depth [m] Distance [m] Time Name Date Place
Static apnea (STA)Men11 min 35 sec Stéphane Mifsud (FRA)2009-06-08Hyères, Var, France
Women9 min 02 sec Natalia Molchanova (RUS)2013-06-29Belgrade, Serbia
Dynamic apnea with fins (DYN)Men300 Mateusz Malina (POL) &
 Giorgos Panagiotakis (GRE)
2016-07-03Turku, Finland
Women237 Natalia Molchanova (RUS)2014-09-26Sardinia, Italy
Dynamic apnea without fins (DNF)Men244 Mateusz Malina (POL)2016-07-02Turku, Finland
Women185 Magdalena Solich (POL)2016-07-02Turku, Finland
Constant weight apnea (CWT)Men128 Alexey Molchanov (RUS)2013-09-19Kalamata, Greece
Women101 Natalia Molchanova (RUS)2011-09-22Kalamata, Greece
Constant weight apnea without fins (CNF)Men102 William Trubridge (NZL)2016-07-20 Dean's Blue Hole, Long Island Bahamas
Women72 Sayuri Kinoshita (JPN)2016-04-26Dean's Blue Hole, Long Island Bahamas
Free immersion apnea (FIM)Men124 William Trubridge (NZL)2016-05-02Dean's Blue Hole, Long Island Bahamas
Women92 Jeanine Grasmeijer (NED)2016-09-06Kralendijk, Bonaire
Variable weight apnea (VWT)Men146 Stavros Kastrinakis (GRE)2015-11-01Kalamata, Greece
Women130 Nanja van den Broek (NED)2015-10-18Sharm el-Sheikh, Egypt
No-limits apnea (NLT)Men214 Herbert Nitsch (AUT)2007-06-14Spetses, Greece
Women160 Tanya Streeter (USA)2002-08-17Turks and Caicos

CMAS recognized world records

As of October 2016, the CMAS recognized world records are:[25]

Discipline Gender Depth [m] Distance [m] Time Name/Country Date Place
Speed 100 m apnea with fins Men00:31.925 Max Poschart (DEU)2016-06-09Lignano, Italy
Women00:37.235 Alina Markovtcova (RUS)2016-06-09Lignano, Italy
STA Static apnea Men10:39.000 Branco Petrovic (SRB)2015-07-30Mulhouse, France
Women08:33.230 Gabriela Grézlová (CZE)2015-07-28Mulhouse, France
DYN Dynamic apnea with fins (50 m pool)Men300.00 Arthur Guérin-Boëri (FRA)2016-06-11Lignano, Italy
Women250.00 Alessia Zecchini (ITA)2016-06-11Lignano, Italy
DNF Dynamic apnea without fins (50 m pool)Men189.65 Olivier Elu (FRA)2016-06-08Lignano, Italy
Women171.22 Alessia Zecchini (ITA)2016-06-08Lignano, Italy
(25 m pool)Men200 Arthur Guérin-Boëri (FRA)2013-08-09Kazan, Russia
Women175 Katarina Zubčić (HRV)2013-11-15Zagreb, Croatia
Jump blue apnea with fins (at sea)Men201.61 Arthur Guérin-Boëri (FRA)2015-10-09Ischia, Italy
Women190.48 Alessia Zecchini (ITA)2015-10-09Ischia, Italy
CWT Constant weight with fins (at sea)Men110 Goran Čolak (HRV)2015-10-06Ischia, Italy
Women93 Alessia Zecchini (ITA)2015-10-06Ischia, Italy
(fresh water)Men75 Michele Tomasi (ITA)2013-09-14Trento, Italy
Women57 Tanya Streeter (USA)1998-12-28Ocala, Fl, USA
CNF Constant Weight without fins (at sea)Men78 Michal Rišian (CZE)2016-10-08Kaş, Turkey
Women60 Alena Konečna (CZE)2016-10-08Kaş, Turkey
(fresh water) Men65 Michal Rišian (CZE)2016-07-10Weyregg, Austria
FIM Free immersion apnea (at sea)Men81 Devrim Cenk Ulusoy (TUR)2012-09-25Kaş, Turkey
Women72 Şahika Ercümen (TUR)2014-07-24Kaş, Turkey
VWT Variable weight apnea with fins (at sea)Men131 Homar Leuci (ITA)2012-09-11Soverato, Italy
Variable weight apnea without fins (at sea)Men81 Devrim Cenk Ulusoy (TUR)2012-09-26Kaş, Turkey
Women91 Şahika Ercümen (TUR)2014-07-23Kaş, 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:

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:

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 his/her system.


The human body has several oxygen-conserving adaptations that manifest under diving conditions as part of the mammalian diving reflex. The adaptations include:


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.[28] 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.[29] 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, special purging deep breaths, hyperventilation. Result of preparation sequence is slower metabolism, lower heart rate and breath rate, lower level of CO2 in bloodstream[30] 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.[9][31] Trained freedivers are well aware of this and will only dive under strict and first aid competent supervision.[32] 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.: 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.[33]

Fiction and documentaries

See also


  1. Dimitri Rebikoff,(1955) Free Diving, Sidgwick & Jackson
  2. David M. Owen,(1955)A Manual for Free-Divers Using Compressed Air, Pergamon
  3. Tailliez, Philippe; Dumas, Frederic; Cousteau, Jacques-Yves; et. al. (1957) The Complete Manual of Free Diving G. P. Putnam's sons, New York
  4. Ivanova, Desislava; Nihrizov, Hristo; Zhekov, Orlin (1999). "The Very Beginning". Human Contact With the Underwater World. Think Quest. Retrieved 2009-09-06.
  5. Sandra Hendrikse; André Merks (12 May 2009). "Diving the Skafandro suit". Diving Heritage. Retrieved 2009-10-16.
  6. 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.
  7. Frost, FJ (1968). "Scyllias: Diving in Antiquity". Greece and Rome (Second Series). Cambridge University Press. 15 (2): 180–5. doi:10.1017/S0017383500017435.
  8. Thucydides (431 BC). History of the Peloponnesian War. Check date values in: |date= (help)
  9. 1 2 Lundgren, Claus EG; Ferrigno, Massimo (eds). (1985). "Physiology of Breath-hold Diving. 31st Undersea and Hyperbaric Medical Society Workshop". UHMS Publication Number 72(WS-BH)4-15-87. Undersea and Hyperbaric Medical Society. Retrieved 2009-04-16.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. "History of Aquathlon". International Aquathlon Association. Archived from the original on June 8, 2004.
  15. "Philosophy of the I.A.A". International Aquathlon Association. Archived from the original on June 8, 2004. Retrieved 6 October 2014.
  16. Cedeño O., Miguel A. (21 February 2009). "The Aquathlon (Fight Underwater) continues its development in 2009". SPORTALSUB.NET.
  17. "Aquatlon". History of CMAS. CMAS.
  18. "The History of Underwater Hockey". Retrieved 2014-08-05.
  19. "CMAS Underwater Hockey Commission". Retrieved 2014-08-05.
  20. "Where is it Played". Retrieved 7 November 2014.
  21. McKie, N (2004). "Freediving in cyberspace.". Journal of the South Pacific Underwater Medicine Society. 34: 101–03. Retrieved 2013-10-05.
  22. AIDA International. "AIDA-disciplines". Retrieved 2015-08-05.
  23. Confédération Mondiale des Activités Subaquatiques. "CMAS-disciplines". Retrieved 2015-08-05.
  24. AIDA International. "World Records". Retrieved 2016-07-03.
  25. Confédération Mondiale des Activités Subaquatiques. "Apnoea Records". Retrieved 2016-10-14.
  26. Wong, R. M. (1999). "Taravana revisited: Decompression illness after breath-hold diving". South Pacific Underwater Medicine Society Journal. 29 (3). ISSN 0813-1988. OCLC 16986801. Retrieved 2008-04-08.
  27. "GO AHEAD, VENT YOUR SPLEEN!", Sarah Milton, 2004, Journal of Experimental Biology
  28. Schagatay E (2009). "Predicting performance in competitive apnoea diving. Part I: static apnoea.". Diving Hyperb Med. 39 (2): 88–99. PMID 22753202. Retrieved 2013-10-06.
  29. Simpson, G; Ferns, J; Murat, S (2003). "Pulmonary effects of 'lung packing' by buccal pumping in an elite breath-hold diver.". Journal of the South Pacific Underwater Medicine Society. 33: 122–126. Retrieved 2016-10-14.
  30. Neal W. Pollock, Richard D. Vann, Edward D. Thalmann and Claus EG Lundgren. (1997). "Oxygen-Enhanced Breath-hold Diving, Phase I: Hyperventilation and Carbon Dioxide Elimination". In: EJ Maney, Jr and CH Ellis, Jr (Eds.) Diving for Science...1997. Proceedings of the American Academy of Underwater Sciences (17th Annual Scientific Diving Symposium). Retrieved 2009-04-16.
  31. Lindholm P, Pollock NW, Lundgren CE (2006). Breath-hold diving. Proceedings of the Undersea and Hyperbaric Medical Society/Divers Alert Network 2006 June 20–21 Workshop. Durham, NC, United States: Divers Alert Network. ISBN 978-1-930536-36-4. Retrieved 2008-04-30.
  32. Fitz-Clarke, JR (2006). "Adverse events in competitive breath-hold diving.". Undersea Hyperb Med. 33 (1): 55–62. PMID 16602257. Retrieved 2013-10-06.
  33. Skolnick, Adam (November 17, 2013). "A Deep-Water Diver From Brooklyn Dies After Trying for a Record". The New York Times. Retrieved November 30, 2013.

Further reading

Look up freediving in Wiktionary, the free dictionary.
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