“Anti-frogman techniques”的意思、由来-开放百科全书

Anti-frogman techniques are security methods developed to protect watercraft, ports and installations, and other sensitive resources both in or nearby vulnerable waterways from potential threats or intrusions by frogmen or other divers.

Risks and threats

In World War II this need for military underwater security was first shown by the achievements of frogmen against armed forces facilities: see for example Italian frogman actions in WWII. Since the late 1950s, the increasing demand for and availability of sophisticated scuba diving equipment has also created concerns about protecting valuable underwater archaeology sites and shellfish fishing stocks.^[1]

The 12 October 2000 USS Cole bombing was not carried out by underwater divers, but did bring renewed attention to the vulnerability they present for naval ships. Divers can swim 100 to 200 yards in three minutes time, and large sonar ranges would need to be established around ships in order for security forces to detect underwater swimmers in time to make a sufficient response.^[2]

In March 2005 the Philippine military, interrogating a captured anti-government terrorist bomber, found that two of Southeast Asia’s most dangerous terrorist organizations linked to Al Qaeda were said to be jointly training militants in scuba diving for attacks at sea.

Scenarios and considerations

Following World War II, the increasing popularity in recreational diving introduced a new complexity to underwater security. Divers must not only be detected, but evaluated as to their purpose or intentions for swimming in monitored areas. Steps to protect against threat or harm from divers must take into account possible reasons why they would be swimming in monitored areas.{{citation needed|date=May 2017}} The divers may be:

Swimmers can approach from the surface or underneath the waters, the two presenting their own detection and deterrence challenges. And the interception and apprehension of intruders detected in bodies of water pose unique safety risks.^[2]

A police-type technique that is reasonably safe on land may be risky to a scuba diver.{{clarify|date=May 2017}}{{citation needed|date=May 2017}}

Sport divers and underwater security

Keeping underwater security against frogman intrusion has been complicated by the expansion of sport diving since the mid-1950s, making it bad policy for most democracies to use potentially lethal methods against any suspicious underwater sighting or sonar echo in areas not officially closed to sport divers. Any routine patrol investigation of all "unidentified frogman" reports would have had to stop because any genuine reports of intruders would be swamped in ever more reports of civilian sport divers who were not in military areas.{{Citation needed|date=December 2010}}

For a long time it would be easy for diving professionals and other experienced divers to distinguish a sport diver with an open-circuit scuba such as an aqualung from a combat frogman with a rebreather; and legitimate civilian divers are normally fairly easy to detect because they dive from land or from a surface boat, rarely or never from an underwater craft, and willingly advertise their presence for their own safety;^[7] but recent multiplication in sport rebreather use may have changed that somewhat.{{citation needed|date=May 2017}}

In the past, when scuba diving was less common, many non-divers, including police, patrol and guards, knew little about diving and did not know of this difference in diving gear, but described all divers as "frogmen". One result was an incident in the inter-ethnic crisis in Cyprus in 1974 when a tourist was arrested for suspected spying because "frogman's kit" was found in his car: it was ordinary sport scuba gear.{{Citation needed|date=December 2010}}

After about 1990 the rapid growth in the number of sport diving rebreather brands has clouded this distinction, while advanced sport divers increasingly tackle longer, deeper, riskier dives using equipment once available only to armed forces or professionals. This means that even "less-lethal" techniques for trapping them underwater, disorienting them, or (especially) forcing them to the surface would be an ever-increasing risk to civilian divers' lives.{{Citation needed|date=December 2010}}

In former times, civilian diving was only for work, and needed standard diving dress and large, readily visible surface support craft. Sport scuba diving has changed that.

Another result of sport diving is a risk of civilians independently re-developing, and then using or selling on the free market, technologies, such as technical advances in underwater communications equipment, formerly kept as military secrets.{{citation needed|date=May 2017}} (For a loss of military secrecy caused by independent civilian duplication, though not underwater, see Lokata Company.)

There have been incidents which have demonstrated poor underwater security, such as when a sport diver with a noisy bubbly open-circuit scuba and no combat training entered a naval anchorage and signed his name on the bottom of a warship.{{Citation needed|date=December 2010}} Concern at the risk of increasing the sport-diving public's ability to penetrate harbors undetected, and of unofficial groups equipping combat frogmen from the sport scuba trade, might have led to the events listed at "#Prevention" below.{{Original research inline|date=May 2017}}{{citation needed|date=May 2017}}

Detection

The MSST (Maritime Safety and Security Team) is a United States Coast Guard harbor and inshore patrol and security team whose methods include detecting submerged divers.{{Citation needed|date=August 2009}}

On the surface

A swimmer on the surface of the water is liable to detection by the same means as used on land, e.g. eyesight, surveillance cameras, thermal imaging, radar.

Underwater

Surveillance of civilian divers

These links [https://web.archive.org/web/20080307100947/http://nucnews.net/nucnews/2002nn/0206nn/020604nn.htm#555#555] {{unreliable source?|date=May 2017}} claim that after 9/11 the FBI asked the USA's largest scuba diver certification organizations to turn over the records of all divers certified since 1998; this turning-over is now done once a year.

Anti-frogman weapons

Some anti-frogman weapons, and weapons that may come to mind when considering defending against frogmen, are:

Attack on the surface or onshore

This is the usual method available to non-diving harbor guards, and to unofficial groups trying to restrict or prevent scuba diving in their area. For weapons, see the next section.

In some circumstances, submerged open-circuit scuba divers can be followed by their bubbles until they run out of air and have to surface, and then tackled on the water surface or as they come ashore.

According to circumstances, the patrol may need some means of transporting prisoners and/or seized diving equipment away from site.{{Citation needed|date=February 2008}}

Many casual sport diving intruders may keep away on seeing visible clearly marked patrol boats and surface barriers.

Police-type or riotsquad-type non-lethal weapons

These methods may be useful when assault-boarding a boat being used by unauthorized or suspect divers, or arresting them onshore, but not often otherwise.

Shooting

Ordinary bullet-firing firearms may be useful (as a lethal weapon) against divers on the surface or men in boats or ashore, but underwater are inaccurate and very short range.{{citation needed|date=May 2017}}

Shotguns (probably pump-action, when used as a security squad weapon) may be effective when the target is out of water, but are even less useful underwater and barrel is likely to explode.{{citation needed|date=May 2017}}

Special underwater firearms have been designed for use underwater: see #Underwater firearms below

Depth charge

A depth charge is effective, and may be lethal, but may cause other damage underwater, and is not recommended in peacetime when the victim may be an intruding civilian sport diver, although it is alleged to have been common practice for some years after 1945 in British naval harbors.{{citation needed|date=May 2017}}

Divers, however, are far less vulnerable to damage by underwater explosion than common sense would dictate. Since the tissues of the body tend to transmit the shock waves with much the same characteristics as the water around, large distant shocks have little impact on divers. For this reason, the most effective "depth charge" for use against a diver is the common hand-grenade, tossed within a few feet of the diver. The resulting gas cavitation and shock-front-differential over the width of the body is effective in stunning or killing the diver.^[13]

Electromagnetic

Visible light

Microwave

The Active Denial System does not work underwater, as water absorbs microwaves well (as in microwave cookers).^[2]

Magnetic field

A magnetic field generator to make the diver's navigation compass misread is possible. Such a magnetic coil carried by a patrol boat directly over the target diver would affect compass readings to 5 meters (15 feet) depth at about 7 kilowatts; but to 10 m (30 feet) (oxygen rebreather depth limit) at about 448 kilowatts, which is too much power need to be practical.^[2]

Sound

There has been much research about the effect of sound on divers.^[2]{{rp|51 et seq}}.

High intensity sound 20–100 Hz, and high intensity impulse noise, are promising as a non-lethal weapon, but more testing is needed.^[2]{{rp|47}} As a source of high-intensity 20–100 Hz sound, the sound generated by a plasma sound source is promising.^[2]{{rp|42–43}}

The US Navy Diving Manual ^[1] says that high-power low-frequency sonar (commonly used for depth sounding and to detect large objects (including submarines)) is not good at detecting small objects like divers, but is hazardous to divers.^[2]{{rp|3}}

Ultrasound

The main effects of ultrasound on the human body are heating and cavitation.^[2]{{rp|21–23}} .

As each wave of the ultrasound passes through the diver, any bubbles in the tissue expand and contract, and the tissue heats. After a particular threshold of loudness of the ultrasound, new bubbles form during the low-pressure part and disappear during the high-pressure part: this is cavitation and can cause injury.{{citation needed|date=May 2017}}

One method is a powerful blast from a ship's ordinary high-power low-frequency sonar (commonly used for depth sounding and to detect large objects (including submarines)), which deranges the diver's inner ear and makes him dizzy and disoriented and tends to force him to surface, or may make him panic and lose his mouthpiece and drown. These large "active sonars" are used to search for submarines and are very powerful. These sonars are usually bow mounted, and if so a diver attacking at the stern would be in the sonar baffle region and unaffected, if he gets close enough first.{{citation needed|date=May 2017}}

Most ships, both military and non-military, carry smaller "navigation" sonars such as depth finders or collision sensors, but their high frequencies and relatively low power lack effectiveness against divers.{{citation needed|date=May 2017}}

A test of a 230 decibel 3000 to 7000 Hz transmitter killed seven whales, causing hemorrhages around their ears: see Sonar#Sonar and marine animals - adverse effects.{{citation needed|date=May 2017}}

Some say that these speculations are mostly fanciful and that since the human body is very close to the impedance of the water around it, the ultrasound tends to pass through the body (perhaps breaking the eardrum, but not killing the diver); but if the sound or ultrasound is powerful it may cause overheating or cavitation damage on the way.{{citation needed|date=May 2017}}{{Original research inline|date=May 2017}}{{weasel inline|date=May 2017}}

It is unknown what later proof or disproof there has been of speculations such as appeared in a book about Cousteau written by Philippe Diole around 1960, about underwater ultrasound guns making an ultrasound beam powerful enough to disintegrate a diver into the water except the metal parts of his kit.{{citation needed|date=May 2017}}{{Original research inline|date=May 2017}}

Audible sound

To cause discomfort to the diver

A sound that irritates or causes pain.^[2]{{rp|27–28}}^[26] Diver aversion to low frequency sound is dependent upon sound pressure level and center frequency.^[27] Westminster International have also implemented this but they withhold the exact sound frequencies used.^[2]

Verbal

The sound may be an order to surrender or surface or go onshore or to the patrol boat, perhaps with a threat to use non-lethal or lethal force if disobeyed. But such an order must be clear enough to be heard and understood.{{citation needed|date=May 2017}}{{Original research inline|date=May 2017}}

Sensitivity to the sound

Underwater, human hearing is largely by bone conduction, through the skull and not through the eardrum and ossicles. This causes somewhat less acuity of hearing and a different graph of sensitivity against frequency, with a loss between 1000 Hz and 5000 Hz. This may affect ability to understand speech.{{citation needed|date=May 2017}}

Research showed that, at depths up to at least 10 m (30 feet), divers' wetsuit hoods lessened underwater hearing sensitivity by 10 to 35 decibels at 1000 Hz and above, and by little or nothing at 250 Hz and below. With increasing depth in a hyperbaric chamber, decreases in wetsuit hood sound attenuation appear only to occur at frequencies between 500 and 1500 Hz.^[29] In the open ocean, hood attenuation at 8,000 Hz showed a significant decrease at 60 fsw and a tendency to decrease at 2,000 and 4,000 Hz compared with the 10 fsw data at the same frequencies in the chamber trials. At frequencies from 500 to 4,000 Hz wetsuit hood sound attenuation was on average 8 dB lower in the ocean than in the chamber trials.^[30]

Underwater, humans are much less able than in air to tell where a sound came from.^[31] Research showed that what ability remains is better with bang!-type noises than with pure tones.^[2]{{rp|28}}^[33]

Electric shock

A newspaper article about the Lionel Crabb disappearance speculated about underwater electric shock weapons mounted on warships to defend them from frogmen. This method, if it is used, imitates nature; see electric eel and electric ray.{{citation needed|date=May 2017}}{{Original research inline|date=May 2017}}

Mechanical devices to capture submerged divers

Such devices occur in fiction, commonly in comics. Some sorts might be possible if designed.

Small dredging-type craft and small submarines are used for small-scale dredging and/or to recover submerged objects; but there is no known case in the real world of them being used to capture divers. The craft's capture device might be a net or a grab or an aimable suction tube or a scoop.

Net

This agrees with talk among diving circles about a fishing trawl being the handiest way for naval men to get unwelcome or unauthorized divers out of the water.

An article at the American Academy of Underwater Sciences 1991 International Symposium

Proceedings says that the California Department of Fish and Game, to capture sea otters underwater for a relocation program, successfully used a net cage apparatus front-mounted on a Dacor Scooter diver propulsion vehicle steered by a diver with a silent bubbleless closed circuit oxygen rebreather. It is not known if a similar larger device has ever been used to capture divers underwater{{Citation needed|date=May 2010}}.

Suction

A suction device might make an area suction effect in the open, or might be a suction tube extended at the frogman, who may be sucked against an opening and so held, or may be sucked inside.^[38]{{rp|36.7}}

Such devices on a small scale are sometimes used in nature to catch prey: for example by the seahorse and the pipefish, and the bladderwort plant. The mouths of many teleost fish (for example centrarchids) have a strong suction component to the way they work.^[39]^[40]

Anti-swimmer barriers

Rigid full-depth netting

There is concern that these nets could interfere with fish migration. Due to this and expense one opinion says that they are a poor choice as frogman excluders.^[2]{{rp|14 et seq.}}

"Marinet" Underwater Security Net Barrier

This is metal chain-link netting placed underwater, preventing entry into an area, or at least delaying the frogmen while they cut through it.{{Citation needed|date=November 2017}}

It was made by an Israeli company, RBtec Perimeter Security Systems. It is a netting constructed of copper or fiber optic cable, covered in polyethylene electrical insulation. The strands are a sensor cable sensitive to cutting or shape bending so that any frogman attack on the net will be detected.{{Citation needed|date=November 2017}} The grid size best suited to deter divers is 250 x 250 mm = 10 x 10 inches but can be modified to any size needed. Testing showed that a diver using bolt cutters could not cut a hole big enough to swim through without being detected.{{Citation needed|date=November 2017}}

In order to prevent attempts of crossing above or under the net the company utilize multiple sensors to detected lifting or climbing of the net.{{Citation needed|date=November 2017}}

The net can also be integrated with sonars and floating barriers for a more complete security solution.

The net system can be equipped with a gate, to allow traffic in and out of the protected area.{{Citation needed|date=November 2017}}

Floating barriers

These will stop surface boats from dropping divers in restricted areas.^[2]{{rp|14 et seq.}}

Flexible full-depth netting

One effective anti-swimmer netting to date is multilayered monofilament line wide-mesh fish netting. It is almost invisible to the diver and difficult to avoid. When equipped with float sensors that detect large-scale movement, these nets have proven highly effective.{{citation needed|date=May 2017}}

Sending other frogmen against them

It would seem that a simple way of countering unknown frogmen or other divers would be for a police force or navy personnel to send their own frogmen to investigate. This is sometimes called counter-offensive frogmen. Combat divers undergo weeks of full-time underwater training, far more and harder than what most civilian sport divers undergo. They would be at full armed forces fitness before frogman training starts: see Frogman#Training. Superior underwater combat training would likely decide which two groups of frogmen would win. Generally, criminal or terrorist frogmen only have access to types of training which are available to civilians, or at least inadequate facilities.

Underwater combat between opposing teams of frogmen (although common in fiction (as in the movie Thunderball, and The Silent Enemy, and at least one incident in Sea Hunt), and often in comics) is unusual in reality.

Sometimes diving sea-police have arrested civilian divers for illegal spearfishing and diving in restricted areas and the like, and naval divers have been sent down to investigate unidentified divers in a naval harbour.

When confronted, sport divers are likelier to obey the patrol divers as ordered. Hostiles would be likelier to fight back.

Among the ways suggested of forcing arrested divers to surface would be attaching an inflatable float to each.^[2]{{rp|11}}

If the patrol divers are riding suitable diver propulsion vehicles, they could travel faster and carry better weapons (lethal or non-lethal) and equipment for sonar search and navigation and communication, and perhaps a means (e.g. grab or net) to capture suspect divers in passing and tow them alongside back to the base or patrol boat.

It was thought expensive for a team of patrol divers to be on standby all the time kitted up to dive. France has police divers trained to arrest unauthorized or suspect divers underwater and to force them to surface. One common offence there is or was spearfishing while using breathing apparatus.

See Frogman#Equipment for features useful in equipment of frogmen who may get into underwater fights.

The Russian PDSS system is an example of an anti-frogman defence system which includes frogmen trained in underwater fights.

See Russian commando frogmen under "1970 and after" for a report of a real underwater fight between a guard squad of Russian PDSS frogmen and intruding enemy frogmen.

The films Above Us the Waves and The Silent Enemy are reconstructions of real World War II events, and each shows an underwater fight between opposing groups of frogmen, but those fights did not happen in the real events.

Underwater firearms

Some navies have thought underwater fights to be likely enough for them to design underwater firearms for frogmen to use as a lethal weapon. There is said to have been a real incident when Russian frogmen shot two anti-frogman dolphins. {{Citation needed|date=February 2015}}

These underwater firearms fire a steel rod, not a bullet, for better range underwater. They are all more powerful than a speargun, and can fire several shots before reloading. Their barrels are not rifled; the fired projectile is kept in line underwater by hydrodynamic effects, and is somewhat inaccurate when fired out of water.{{citation needed|date=May 2017}}

Other underwater man-carried weapons

Trained animals, as weapons

A reported anti-frogman guard is (or was) dolphins trained to carry on the nose a device which injects a large amount of compressed carbon dioxide into the frogman. This would likely be lethal due to blood embolism. It is said that they were trained at Point Mugu. It was said that this device was abandoned because of fears that wild dolphins might imitate and start harassing ordinary divers. Today the mammals are primarily trained to force the diver to the surface using pushing techniques in the assumption that the majority of incursions can be addressed in this manner.{{citation needed|date=May 2017}}

The US Navy has deployed sea lions to detect divers in the Persian Gulf.^[3] The sea lion is trained to detect the diver, connect a marker buoy to his leg by a C-shaped handcuff-like clamp, surface, and then bark loudly to raise the alarm. 20 sea lions have been trained for this at the US Naval Warfare Systems Center in San Diego. Some have been flown to Bahrain to help the Harbor Patrol Unit to guard the US Navy's 5th Fleet. Sea lions adapt easily to warm water, can dive repeatedly and swim up to 25 mph, can see in near-darkness, and can determine the direction of underwater sound. In training the sea lions have been known to chase divers onto land. See also this link.

In 1970 to 1980 trained dolphins killed 2 Russian frogmen who were putting limpet mines on a US cargo ship in Cam Ranh bay in Vietnam.^[4] Subsequently, Russian PDSS frogmen were trained to fight back against trained dolphins. In an incident on the coast of Nicaragua PDSS frogmen killed trained anti-frogman dolphins. Arrival of underwater rifles and pistols seems to make the trained animal threat less.{{citation needed|date=May 2017}}

Animals, unlike ROVs etc., need to be fed and kept in training whether they are needed at work or not, and cannot be laid aside in a storeroom until needed.{{citation needed|date=May 2017}}

Remote-controlled underwater vehicle, as weapon

A ROV, as well as searching, could be equipped to arrest or attack divers on command, but with their technology as it is could not attack several targets one after another as quickly as a marine mammal. A surface-only ROV would need a long-range weapon to be effective against deeply submerged suspect divers.{{citation needed|date=May 2017}}{{Original research inline|date=May 2017}}

Prevention

Preventing public access to frogman-type diving gear, or to any diving gear

Prevention technology

Technology exists where underwater speaker systems can be deployed around the designated area.^[47]{{dead link|date=May 2017}} This array of speaker systems can be programmed to send high powered frequencies which then blasts powerful 'disruption' signals into the water. The frequencies have a maximum disorientation effect on the diver(s), which induce discomfort or panic causing them to leave the area or surface for interception. In cases where the divers remain in the water, the frequencies are likely to have a continued adverse effect which could cause sickness and confusion.{{citation needed|date=May 2017}}

Preventing public access to water

For sport divers and similar who have no means of covert entry, one method is merely to try to stop all divers from reaching water, or stopping them from using boats, in some particular place or area. Such a bylaw may be called for by the military to keep sport divers away from secret underwater sites, or by inshore fishermen to stop alleged poaching of shellfish.{{citation needed|date=May 2017}}

The US has made many such regulations to protect such infrastructures as power plant and nuclear plant water intakes and discharges, bridge foundations, harbor and pier installations, and naval facilities.{{citation needed|date=May 2017}}

The Socialist Federal Republic of Yugoslavia (until its demise) forbade all sport diving except a few Government-controlled groups, and required official permission for each campaign of archaeological or scientific diving.{{citation needed|date=May 2017}}

References

1. ^[https://web.archive.org/web/20061208064816/http://www.coralspringsscuba.com/miscellaneous/usn_manual.htm ](page 24)
2. ^http://www.wi-ltd.com/defence/Maritime_Defence/Acoustic_Defence_Systems Enforcer_Underwater_CommunicationDiver_Disruption_System
3. ^{{Cite web|url=http://www.divernet.com/news/items/sealion250203.htm|title=Sea Lions Deployed to Detect Divers in Persian Gulf|last=|first=|date=|website=|archive-url=https://web.archive.org/web/20060512074525/http://www.divernet.com/news/items/sealion250203.htm|archivedate=May 12, 2006|dead-url=|accessdate=}}
4. ^{{Cite web|url=http://specialoperations.com/Foreign/Russia/Naval_Units.htm|title=Delfin (Dolphin)|last=|first=|date=|website=|archive-url=https://web.archive.org/web/20051202112154/http://specialoperations.com/Foreign/Russia/Naval_Units.htm|archive-date=December 2, 2005|dead-url=|access-date=}}
5. ^¹{{cite journal |author=Carroll, Andrew M |title=Muscle activation and strain during suction feeding in the largemouth bass Micropterus salmoides |journal=Journal of Experimental Biology |year=2004 |pages=983–991 |volume=207 |doi=10.1242/jeb.00862 |url=http://jeb.biologists.org/cgi/content/abstract/207/6/983 |accessdate=2009-02-22 |pmid=14766957 |issue=Pt 6}}
6. ^¹{{cite journal |author1=Carroll, Andrew M |author2=Wainwright, Peter C |author3=Huskey, Stephen H |author4=Collar, David C |author5=Turingan, Ralph G |title=Morphology predicts suction feeding performance in centrarchid fishes |journal=Journal of Experimental Biology |year=2004 |pages=3873–3881 |volume=207 |doi=10.1242/jeb.01227 |url=http://jeb.biologists.org/cgi/content/abstract/207/22/3873 |accessdate=2009-02-22 |pmid=15472018 |issue=Pt 22}}
7. ^¹{{cite journal |author1=Cudahy, E |author2=Parvin, S |title=The Effects of Underwater Blast on Divers. |journal=US Naval Submarine Medical Research Lab Technical Report |volume=NSMRL-1218 |year=2001 |url=http://archive.rubicon-foundation.org/7518 |accessdate=2008-08-12 }}
8. ^¹{{cite web|url=http://www.wg-plc.com/international/defence/enforcer+underwater+diver+disruption.html |title= |last= |first= |work= |accessdate= |deadurl=yes |archiveurl=https://web.archive.org/web/20090406105610/http://www.wg-plc.com/international/defence/enforcer%2Bunderwater%2Bdiver%2Bdisruption.html |archivedate=6 April 2009 }}
9. ^¹{{cite journal |author=Feinstein SH |title=The accuracy of diver sound localization by pointing |journal=Undersea Biomed Res |volume=2 |issue=3 |pages=173–84 |date=September 1975 |pmid=15622737 |doi= |url=http://archive.rubicon-foundation.org/2429 |accessdate=2008-08-12}}
10. ^¹{{cite journal |vauthors=Fothergill DM, Sims JR, Curley MD |title=Recreational scuba divers' aversion to low-frequency underwater sound |journal=Undersea Hyperb Med |volume=28 |issue=1 |pages=9–18 |year=2001 |pmid=11732884 |doi= |url=http://archive.rubicon-foundation.org/2368 |accessdate=2008-08-12}}
11. ^¹{{cite journal |author1=Fothergill, DM |author2=Cudahy, EA |author3=Schwaller, D |title=The effect of depth on underwater sound attenuation of a neoprene wetsuit hood: Hyperbaric chamber trials. (abstract)|journal=Undersea Hyperb Med |volume=31 |issue=1 (supplement) |pages= |year=2004 |pmid= |doi= |url=http://archive.rubicon-foundation.org/1515 |accessdate=2008-08-12}}
12. ^¹{{cite journal |author1=Fothergill, DM |author2=Cudahy, EA |author3=Schwaller, D |title=Open ocean trials of the effect of depth on underwater sound attenuation of a neoprene wetsuit hood. (abstract)|journal=Undersea Hyperb Med |volume=31 |issue=1 (supplement) |pages= |year=2004 |pmid= |doi= |url=http://archive.rubicon-foundation.org/1515 |accessdate=2008-08-12}}
13. ^¹{{cite journal |vauthors=Hollien H, Hicks JW, Klepper B |title=An acoustic approach to diver navigation |journal=Undersea Biomed Res |volume=13 |issue=1 |pages=111–28 |date=March 1986 |pmid=3705246 |doi= |url=http://archive.rubicon-foundation.org/3061 |accessdate=2008-08-12}}
14. ^¹²³⁴⁵⁶⁷⁸⁹¹⁰¹¹¹²¹³¹⁴¹⁵¹⁶¹⁷¹⁸¹⁹²⁰²¹²²²³²⁴²⁵²⁶²⁷²⁸{{Cite report | title = Non-Lethal Swimmer Neutralization Study | year = 2002 | place=San Diego | publisher = SSC San Diego, United States Department of the Navy | url = http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/7519/ADA406644.pdf?sequence=1 |format=PDF| accessdate=2008-02-07 | work = first Applied Research Laboratories, University of Texas at Austin }}
15. ^¹{{cite web |title=Surveillance and Protection of Underwater Archaeological Sites: Sea Guard |author=Akal, Tuncay |publisher=The Acoustical Society of America |url=http://www.acoustics.org/press/155th/akal.htm |accessdate=2009-02-22 |archive-url=https://web.archive.org/web/20081115170600/http://www.acoustics.org/press/155th/akal.htm |archive-date=15 November 2008 |dead-url=yes |df=dmy-all }}
16. ^¹{{cite journal |vauthors=Steevens CC, Russell KL, Knafelc ME, Smith PF, Hopkins EW, Clark JB |title=Noise-induced neurologic disturbances in divers exposed to intense water-borne sound: two case reports |journal=Undersea Hyperb Med |volume=26 |issue=4 |pages=261–5 |year=1999 |pmid=10642074 |doi= |url=http://archive.rubicon-foundation.org/2333 |accessdate=2008-08-12}}
17. ^¹{{cite book |author=Stellman, Jeanne Mager |title=Encyclopaedia of Occupational Health and Safety |isbn=92-2-109203-8 |publisher=International Labour Organization |year=1998 |url=https://books.google.com/books?id=Ceuq9P4hLJMC&pg=RA1-PT34&lpg=RA1-PT34&dq=diver+entrapment+suction |accessdate=2009-02-22}}
18. ^¹{{cite web|url=http://www.tribuneindia.com/2001/20010218/spectrum/nature.htm |title=They use sound to kill|first= Nutan |last=Shukla|date=18 February 2001 |work= Spectrum - Nature |publisher=The Sunday Tribune |accessdate=19 May 2017 }}
19. ^¹{{cite web|last=Whitten|first=Chris|title=Dive Flag Law|url=http://www.dive-flag.com/law.html|publisher=Dive-Flag|accessdate=7 July 2012}}