Saturday, 25 February 2012

Scuba Diving Hand Signals - Learning to Scuba Dive

Scuba Diving hand signals are vital information for all scuba divers. Whether you are a beginner or seasoned diver you will always need to ensure you remember the key hand signals which ensure good buddy communication. Without good communication with your buddy you undoubtedly take risks. The following scuba diving hand signals are the standard list of hand signals required to enable you to communicate with your dive buddy. 
Scuba Diving Hand Signals - Learning to Scuba Dive


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Saturday, 18 February 2012

Full List of PADI Courses & PADI Courses Flow Chart

Here you will find the PADI Courses flow chart for all PADI Courses. This flow chart is helpful to follow which courses are pre requisites to enable you to plan your progression and PADI certification route.


PADI Courses Flow Chart


At the Chikarma Diving blog we will be providing detail blog entries on all PADI scuba diving Courses. Come back and check out the Course details when required. 



Here is a full list of PADI Scuba Diving Courses


Diver-Level Courses
Online Courses with PADI eLearning®


Open Water Diver Online 
Scuba Tune-Up Online 
Advanced Open Water Diver Online 
Rescue Diver Online 
Enriched Air Diver Online 
Digital Underwater Photographer Online 
Dive Theory Online 
Divemaster Online 
Instructor Developement Online 


Get Introduced
Discover Scuba Diving (10yrs+) 
Bubblemaker (8yrs+) 
Seal Team (8yrs+) 
Skin Diver 


Get Certified
Open Water Diver (10yrs+) 
Scuba Diver


Improve Your Skills
Advanced Open Water Diver 
Adventure Diver 
Master Scuba Diver 


Be a Safer Diver. Be Prepared
Rescue Diver
Emergency First Response 
Emergency Oxygen Provider 


Taste the Fun and Adventure
Altitude Diver 
AWARE Fish ID 
Boat Diver 
Cavern Diver 
Coral Reef Conservation Diver 
Deep Diver 
Digital Underwater Photographer 
Diver Propulsion Vehicle Diver 
Drift Diver 
Dry Suit Diver 
Enriched Air Diver
Equipment Specialist 
Ice Diver 
Multilevel Diver 
National Geographic Diver 
Night Diver 
Peak Performance Buoyancy 
Project AWARE Specialist 
Search and Recovery Diver 
Semiclosed Rebreather 
Underwater Naturalist 
Underwater Navigator 
Underwater Videographer 
Wreck Diver


Technical Courses
Discover Tec Diving 
Tec 40 
Tec 45 
Tec 50 
Tec Trimix 65 
Tec Trimix Diver 
Tec Gas Blender 


Professional Courses
Become a PADI Pro
Divemaster 
Assistant Instructor 


Teach Scuba
Open Water Scuba Instructor
Specialty Instructor 
Master Scuba Diver Trainer Rating 
Master Instructor Rating


Teach Technical Diving
Tec Instructor 
Tec Deep Instructor 
Tec Gas Blender Instructor 
Tec Trimix Instructor


Teach Professional Instructor Training
IDC Staff Instructor 
Course Director 


Teach CPR and First Aid
Emergency First Response Instructor

List of Scuba Diving International Organisations/Organizations

This page lists Scuba diver training organisations/organizations. These include cave diving, commercial diving, recreational diving, technical diving, and other related organisations/organizations.


Cave diving training organisations/organizations


CDDA - Cave Divers Association of Australia
CDG - Cave Diving Group
GUE- Global Underwater Explorers
NACD - National Association for Cave Diving
NSS - CDS - National Speleological Society Cave Diving Section
PROTEC - Professional Technical Diving
PSAI - Professional Scuba Association International
UTD - United Team Diving


Surface supplied air training organizations/organisations:
International Diving Institute 

Scuba training organizations:
aa - Aquanaut Academy International 
ACUC - American Canadian Underwater Certifications 
ADAS-Autonomus divers association of scuba diving 
ADS - Association of Diving School 
AED - Associated European Divers 
ANDI - American Nitrox Divers International, also ANDI International
ANMP - Association nationale des moniteurs de plongée 
ATEC - Association of Technical and Recreational Scuba Diving Instructors 
AUSI - Associated Underwater Scuba Instructors 
BSAC - British Sub Aqua Club 
CEDIP - European Committee of Professional Diving Instructors 
CIMAS - Corporación de Instructores Mexicanos en Actividades Subacuáticas
CMAS - Confédération Mondiale des Activités Subaquatiques 
CMAS AMERICAS - CMAS AMERICAS - US Federation of CMAS 
DIWA - Diving Instructor World Association - International Federation of DIWA 
DFPA - Diving Friends Poland Association
FAUI - Formation of Australian Underwater Instructors
FFESSM - Fédération Française d'Études et de Sports Sous-Marins 
FIAS - Federazione Italiana Attività Subacquee 
FIPSAS - Federazione Italiana Pesca Sportiva e Attività Subacquee 
RUF - Russian Underwater Federation 
GUE - Global Underwater Explorers
HSA - Handicap Scuba Association 
IADS - International Association of Diving Schools
IAHD - International Association for Handicapped Divers 
IANTD - International Association of Nitrox and Technical Divers 
IDEA - International Diving Educators Association 
IDIA - International Dive Instructors Association 
ISDA - International Scuba Diving Academy
ISEA - International Scuba Educator's Association 
ISE - Inner Space Explorers Los Angeles County Underwater Instructors Association (Division of LA County Parks & Recreation) 
Microdive - Microdive Scuba Training Agency
NACD - National Association for Cave Diving
NASDS - National Association of Scuba Diving Schools (recently merged with SSI)
NASE - National Academy of Scuba Educators 
NAUI - National Association of Underwater Instructors 
NOB - Nederlandse Onderwatersport Bond 
PADI - Professional Association of Diving Instructors 
PDA - Professional Diving Association 
PDIC - Professional Diving Instructors Corporation International 
PROTEC - Professional Technical & Recreational Diving 
PSS - Professional Scuba Schools 
SAA - The Sub-Aqua Association 
SDI - Scuba Diving International
SEI - Scuba Educators International 
SRS - Sea Research Society 
SSAC - The Scottish Sub Aqua Club 
SSI - Scuba Schools International 
SNSI - Scuba Nitrox Safety International
TAC - The Aquatic Club - existed in the UK between 1982 and 1986. dissolved organization
UEF - Underwater Explorers' Federation 
UDI - United Diving Instructors 
UDT - Universal Diver Training 
USAS- United Sub Aqua Society 
UTD - Unified Team Diving 
WOSD - World Organisation of Scuba Diving 
YMCA SCUBA - dissolved organization

Scientific organizations/organisations:
AAUS - American Academy of Underwater Sciences
CAUS - Canadian Association for Underwater Science
The Scientific Committee of CMAS
SDSC - "Scientific Diving Supervisory Committee

Technical diving training organizations/organisations:
ANDI - American Nitrox Divers International 
ATEC - Association of Technical and Recreational Scuba Diving Instructors 
BSAC - British Sub Aqua Club 
DIWA - Diving Instructor World Association - International Federation of DIWA 
DRI - Dive Rescue International 
DSAT - Diving Science and Technology  - Merged into PADI in 2010
DFPA - Diving Friends Poland Association
FIAS - Federazione Italiana Attività Subacquee 
GUE - Global Underwater Explorers 
ANTD - International Association of Nitrox and Technical Divers 
IART - International Association of Rebreather Trainers 
ITDA - International Technical Diving Association 
LACUIA - Los Angeles County Underwater Instructors Association (Division of LA County Parks & Recreation) 
NAUI-Tec - NAUI Tec 
PADI - Professional Association of Diving Instructors 
PDIC - Professional Diving Instructors Corporation 
PRONRC - Professional Nitrox & Rebreather College 
PROTEC - Professional Technical Diving 
PSAI - Professional Scuba Association International
PSS Technical Training - Professional Scuba Schools 
TDI - Technical Diving International 
TXR - Scuba Schools International Technical Extended Range 
UDT - Universal Diver Training 
UTD - Unified Team Diving 

Other Scuba Diving Organisations/organizations
Active Divers Association
AISI- Association of Italian Diving Enterprises 
ARSBC - Artificial Reef Society of British Columbia
AUC - Alberta Underwater Council 
BFDC and North Carolina SCUBA/Wreck Diving
Chicago Aquanauts Scuba Association
DAN - Divers Alert Network 
DDRC - Diving Diseases Research Centre 
ERDI - Emergency Response Diving International
EUF - European Underwater Federation 
FRO - Frontier - THE SOCIETY FOR ENVIRONMENTAL EXPLORATION 
GLACD - Greater Los Angeles Council of Divers
Global Vision International - Diver Training combined with marine conservation 
GODIVECYPRUS - Cyprus Diver Training 
Historical Diving Society
HSA International [Handicapped Scuba Association] 
IADRS - International Association of Dive Rescue Specialists 
Israeli Diving Federation
Malta Professional Diving Schools Association
National Association of Black Scuba Divers 
Nautical Archaeology Society
New York State Diver's Association
Recreational Divers Association
Sea Research Society - Shipwreck consulting & underwater archaeology
TSA - Trimix Scuba Association
UKSDMC - UK Sports Diving Medical Council 
USDDA - United States Dental Diving Association, Inc.
Yomps - Diver Training all over the world and also marine conservation 
ITDA - International Technical Diving Association 



Sunday, 12 February 2012

HMS Maori: Scuba Diving Sites Malta & Dive Sites Gozo


HMS Maori (L-24/F-24/G-24) was a Tribal-class destroyer laid down by the Fairfield Shipbuilding and Engineering Company, Limited, at Govan in Scotland on 6 June 1936, launched on 2 September 1937 by Mrs. W. J. Jordan and commissioned on 2 January 1939. She was named after the indigenous Māori people of New Zealand, and Mrs Jordan was the wife of the New Zealand High Commissioner William Jordan.
HMS Maori - Scuba Diving Sites Malta / Scuba Diving Sites Gozo
Maori served with the Mediterranean Fleet, was involved in the pursuit and destruction of the enemy German battleship Bismarck in May 1941, and served with the 14th Destroyer Flotilla during the Battle of Cape Bon in December 1941. Maori, commanded by Commander R. E. Courage, RN, was attacked by enemy German aircraft and sank at her moorings in the Malta Grand Harbour on 12 February 1942 with the loss of one of her crew. She was raised and scuttled off Malta on 15 July 1945.
Located a few hundred metres from the shore from Valletta, HMS Maori is now a popular dive site. The bow section lies in white sand at a depth of 14m, the aft section of the ship having been abandoned in deep water during the tow from Grand Harbour to Marsamxett Harbour. Much of the forward superstructure is still extant, including the two front gun bases. Much marine life can be found on the wreck.
For further information on scuba diving services in Malta & Gozo please click here. 

MV Rozi - Gozo: Scuba Diving Sites Malta & Dive Sites Gozo

MV Rozi - Scuba Diving Sites Malta / Scuba Diving Sites Gozo

MV Rozi was a Bristol built tugboat launched in 1958 as the Rossmore by Charles Hill & Sons Ltd. In 1969 she was sold to Rea Towing Company and renamed Rossgarth. In 1981 she was sold to Tug Malta, and renamed Rozi, operated in Grand Harbour Valletta. 
Rozi was scuttled in 1992 off Ċirkewwa as an artificial reef and attraction for Captain Morgan's Underwater Safari Tours. The submarine no longer operates, but the wreck is a popular diving attraction sitting upright, intact except for its engines and propeller, on a sandy bed at a depth of 35 metres (115 ft).
For further information on scuba diving services in Malta & Gozo please click here. 

Um El Faroud: Scuba Diving Sites Malta & Dive Sites Gozo


The Um El Faroud is the wreck of a Libyan motor tanker that was being worked on in a dry dock in Malta when a gas explosion on board killed nine Maltese dockworkers. For three years after the 1995 explosion she lay in the harbor of Valletta, then she was moved to the current location. She sits upright on the sandy seabed southwest of Wied iz-Zurrieq. The Um El Faroud weighs 10,000 tons and is 115 metres (377 ft) long.The depth to the top of the bridge is 18 metres (59 ft) and 25 metres (82 ft) to the main deck. Scuba divers might come across some squid and barracudas at the stern. The wreck can be entered fairly easily, but due to its size, this should be restricted only to divers with advanced wreck diving training.
Um El Faroud: Scuba Diving Sites Malta & Scuba Diving Sites Gozo
M/t Um El Faroud was built in 1969 at Smith Dock Co. Ltd, Middlesbrough, England and was owned by the General National Maritime Transport Company, Tripoli (GNMTC). She had been operating between Italy and Libya carrying refined fuel up to 1 February 1995. On 3 February 1995 she was docked at No.3 Dock of Malta Dry-docks. During the night of 3 February an explosion occurred in No.3 centre tank and nine shipyard workers lost their lives. The vessel suffered structural deformation and, following inspection and survey, was considered a total write-off. She occupied the dock after the explosion until it was decided that the best option to utilize her remaining value was to scuttle her as a diving attraction and to start a new life as an artificial reef. The vessel measures 109.53 metres (359.4 ft) in length, and has a beam of 15.5 metres (51 ft); the height of the vessel from keel to funnel top is approximately 22 metres (72 ft). Um El Faroud was a single screw motor tanker.After a bad storm in winter 2005/6 the ship has now broken in two. ref. 
For further information on scuba diving services in Malta & Gozo please click here.

Inland Sea - Gozo: Scuba Diving Sites Malta & Dive Sites Gozo


The Inland Sea, sometimes called Qawra in Maltese, is a lagoon of seawater on the island of Gozo linked to the Mediterranean Sea through an opening formed by a narrow natural arch.
Inland Sea - Gozo: Scuba Diving Sites Gozo & Scuba diving sites Malta
It was probably formed where a geological fault in the limestone had created a sea cave and the roof then collapsed. 
On one side there is a gently shelving stony beach with several fishermen's huts. The boats are often pulled up on to the stony beach. The bottom of the lagoon is also mostly pebbles and rocks and is fairly shallow. As you exit through the tunnel towards open sea, the floor drops away in a series of shelves to a depth of up to 35 metres on the outside. Jacques Cousteau said the Inland Sea was among his top ten dives. 

On calm days fishing boats, known in Maltese as luzzijiet, can pass through the tunnel. Some of the boats are used to take visitors through the archway and then for a tour of the nearby cliffs and other sites, mainly to the Fungus Rock and another large natural arch in the cliffs called the Azure Window.
For further information on scuba diving services in Malta & Gozo please click here. 

Azure Window: Scuba Diving Sites Malta & Dive Sites Gozo


The Azure Window (Maltese: Tieqa Żerqa) is a natural arch in the Maltese island of Gozo featuring a table-like rock over the sea. It is situated near two other famous natural landmarks - the Inland Sea, and Dwejra Bay. The stunning geography of the area was created thousands of years ago when two limestone caves collapsed. This and the nearby Blue Hole and Inland sea are popular scuba diving sites.
Azure Window - Scuba Dive Sites Malta / Scuba Diving Sites Gozo
Dwejra is a tourist village that belongs to the town of St. Lawrence, Gozo, Malta. Dwejra Bay is also part of San Lawrenz. The water of the bay is suitable for swimming, scuba diving, and boating.
The Azure Window has been featured in films, such as Clash of the Titans (1981) at the 104th minute and The Count of Monte Cristo (2002) at the 13th minute. It can also be seen in the television miniseries The Odyssey (1997), and HBO's TV series Game of Thrones. The filming of Game of Thrones resulted in controversy when a protected ecosystem was damaged by a subcontractor.
The Azure Window was recently measured by surveyor Noe Ardanaz of The University of Edinburgh. The height was given as 22.54m, slightly higher than the previous unofficial estimates of 18 to 20 metres.
Although illegal, the Azure Window is a popular cliff diving or tomb-stoning spot. Many videos on YouTube feature people leaping from the middle, and side of the arch.
The arch of the Azure Window is disintegrating, as large pieces of rock keep falling from the arch. It is expected that the arch will completely disappear within just a few years. The arch is in a dangerous condition and warning notices are placed to stop people walking over the top of the arch. Evidence of this can be seen when the images of the Azure Window as shown in Clash of the Titans (1981) are compared to the more recent images shown in The Odyssey (1997) and The Count of Monte Cristo (2002). The former images depict the Azure Window arch with a flat underside, whereas the latter images clearly show that a significant proportion the flat underside has since broken away. Once the arch has completely crumbled away, the Azure Window shall be renamed Azure Pinnacle. 
For further information on scuba diving services in Malta & Gozo please click here. 

Scuba Diving Decompression Sickness: The Bends & Caisson Disease:Cerebral Arterial Gas Embolism (CAGE)


This is caused by rupture of the fragile lining of the lung's alveoli allowing large quantities of air to enter the blood vessels leading to the small arteries in the brain via the heart.
Cerebral Arterial Gas Embolism is the result of pulmonary barotrauma usually caused when a diver runs out of air. This will often result in a panic reaction, with breath-holding and rapid ascent to the surface leading to over expansion of the lungs as the volume of air in them increases with decreasing ambient water pressure (Boyle’s Law).
Signs and Symptoms of CAGE
Cerebral Arterial Gas Embolism is the result of pulmonary barotrauma, which may present with the following symptoms.
·         Subcutaneous emphysema, particularly around collarbone area.
·         Chest pain.
·         Shortness of breath (dyspnoea).
·         Coughing, possibly with blood (haemoptysis).
·         Increase in heart rate (tachycardia).
·         Decrease in blood pressure (hypotension).
The resulting cerebral damage may result in the following symptoms.
·         Severe headache.
·         Paralysis.
·         Numbness.
·         Unconsciousness.
Symptoms similar to those of neurological DCS may also be present. Any confusion between the diagnosis of CAGE or neurological DCS should not influence the immediate care of the affected diver, as both are medical emergencies treated initially in the same way.
Treatment of DCS (CAGE and DCI) 
Initial treatment for all suspected cases of decompression illness, whether thought to be DCS or CAGE, should be the same. Firstly, the accepted practice of "Safety, ABC" should be used.
·         Safety first - do not place yourself at risk of becoming another casualty, it is more difficult to treat two divers than just one.
·         If unconscious, place the casualty in the recovery position and ensure airway is open.
·         Administer high concentration oxygen if available.
·         Perform CPR if required.
·         Seek medical assistance immediately- see the contact section for details.
In addition, rescuers should ensure the following.
·         Lay the casualty down and keep them horizontal - this may help prevent bubble migration to the brain.
·         Encourage the diver to remain calm and still.
·         Protect against hypothermia - replace wet clothes with dry. Do not expose to excessive heat.
·         Encourage fluid intake (aim for 1 litre in the first hour) - if the casualty has a reduced conscious level or has difficulty in swallowing then avoid giving oral fluids. If available, intravenous fluid therapy is preferred.
·         Monitor for deterioration and record observations.
·         Notify the appropriate emergency service of any deterioration.
·         Do not give opiates as this may reduce respiratory rate and prolong nitrogen off-loading.
·         Never administer Entonox ("gas and air"), as this will worsen the condition due to its high nitrogen content.
Recompression Therapy
The definitive treatment for any form of decompression illness is recompression in a hyperbaric chamber.
The main purpose of this is to reduce the size of any existing bubbles. In addition, 100% oxygen is given in order to encourage the excretion of nitrogen from the body.
Symptoms may persist due to existing tissue damage and the accumulation of blood cells, etc, around the points where bubbles were situated.
At the Hyperbaric Medicine Unit in Aberdeen the most common therapy for bends is based on a modified U.S. Navy Table 6 profile. In this treatment, the patient is compressed to nearly three times normal atmospheric pressure, which equates to a depth of 18msw.
Depending on the patient's condition during the treatment, the table may be extended, or changed to a Heliox (HeO2) saturation table lasting several days. 

Scuba Diving Decompression Sickness: The Bends & Caisson Disease: Signs and Symptoms of DCS


Diagnosis is based mainly on the patient’s history. For example, an 80 year old lady in A&E complaining of a painful shoulder, shopping bags by her trolley, is unlikely to have DCS – whereas a 20 year old with the same presenting symptoms and a SCUBA tank next to them is a likely candidate for recompression treatment.
A useful description of DCS can be achieved by noting the area(s) of the body affected.
General signs (constitutional).
·         Nausea, weakness or fatigue.
Skin (cutaneous).
·         Itching (pruritis).
·         Generalised rash.
·         Lumps.
·         Cutis marmorata marbling (serious sign).
·         Crackling feeling (subcutaneous emphysema) - not usually around collarbone.
Musculoskeletal (muscles and joints).
·         Joint or muscle discomfort and / or pain ("bends").
·         Limitation of limb movement.
·         Crunching sound in joint. 
Gastrointestinal (stomach and bowel).
·         Nausea, vomiting.
·         Abdominal cramps, diarrhoea.
Cardiorespiratory (heart and lungs).
·         Coughing.
·         Chest pain made worse on inspiration.
·         Tachypnoea (increase in breathing rate).
Neurological (cerebrum, cerebellum, spinal cord, inner ear and peripheral nerves).
·         Headache.
·         Confusion.
·         Memory loss.
·         Tremors.
·         Visual disturbance (scotoma).
·         Involuntary eye movement (nystagmus).
·         Lack of co-ordination (AtAxia).
·         Numbness or altered sensation.
·         Pins and needles (paresthesia).
·         Urinary retention / incontinence.
·         Ringing sound in ears (tinnitus).
·         Hearing loss.
·         Dizziness, loss of balance (vertigo).
·         Partial or full paralysis of lower limbs (paraparesis / paraplegia).
·         Unconsciousness.
The “Rhomberg test” is commonly used to assess a patient with suspected DCS. The patient is asked to stand heel to toe, with legs slightly bent at the knees. They then cross the arms with them lifted off the chest and close their eyes. Those with neurological DCS are unlikely to be able to maintain their balance for more than a second or two.
It must be emphasised that even in the absence of obvious symptoms, the possibility of DCS should be considered if the diver's circumstances suggest such a risk. Those with any symptoms of DCS, however mild, are at risk of further episodes.
Classification of DCS
Decompression sickness can be classified as either Type 1 or Type 2. The different classification reflects the effect, and therefore the severity, of the condition.
Type 1 DCS can occur when bubbles affect the tissues around skeletal joints. The areas most often affected are the knees, elbows and shoulders.
Decompression sickness might also present as a skin (cutaneous) disorder. Nitrogen bubbles can cause mottling, lumps or a rash. "Skin bends", as they are colloquially termed, are more common during hyperbaric chamber 'dives' and when diving using a dry suit. Although not usually in themselves serious, skin symptoms may indicate the presence of problems elsewhere. If left untreated, Type 1 DCS may progress to Type 2.
Type 2 decompression sickness reflects involvement of the Central Nervous System (CNS) and / or the cardio-respiratory system. More than half of those diagnosed with DCS will be classified as Type 2. Cerebral symptoms arise from interruption of the blood supply to the main part of the brain, and include confusion, reduced mental function and unconsciousness. Involvement of the cerebellum may lead to tremors, loss of balance ("staggers") and a lack of co-ordination (ataxia). Balance may also be affected by damage to the vestibular part of the inner ear.
Spinal DCS may present as back pain, paresthesia (pins and needles), paralysis and loss of urinary sphincter control - resulting in either incontinence or retention.
As discussed already, the formation of small inert gas bubbles does not necessarily lead to the development of DCS. Likewise, when bubbles become trapped in the tiny blood vessels around the lungs' alveoli (air sacs), problems do not always arise. In fact, it is thought that their accumulation in this area may increase the rate that the gas is excreted from the body (Edmonds et al, 1993). However, if too many bubbles collect, breathing will become adversely affected ("chokes"). Symptoms include breathlessness, tachypnoea, chest pain and coughing. Although symptoms may resolve, this should be regarded as a life-threatening condition as it may progress to fatal respiratory collapse. 

Scuba Diving Decompression Sickness: The Bends & Caisson Disease: Predisposing Factors


The risk of developing decompression sickness depends on many factors, most of which are not yet clearly understood. Some of these are discussed below.

Flying After Diving
Because there are fewer molecules of gas at higher altitude, there is less pressure and therefore a lower partial pressure of each gas in the air - which means there is less oxygen available. This hypobaric effect is the opposite of hyperbaric pressure.
This concept is familiar to most people since aircraft flying at high altitudes must have pressurised cabins to support life. All commercial passengers are reminded that in the event of sudden cabin decompression oxygen masks will drop down from above. In normal operation the cabin 'altitude' can be as high as 7,500 - 8,000 feet.
Although reducing the available amount of oxygen to the body can lead to hypoxic conditions, most healthy people will not experience symptoms during a normal commercial flight. The main risk to divers from flying is not the reduction in oxygen partial pressure, but the reduction in atmospheric pressure itself.
The degree of change in a hypobaric atmosphere is less pronounced than in a hyperbaric atmosphere, but pre-existing nitrogen bubbles in the body will grow larger and may exacerbate or even cause DCS. Larger gas spaces, such as a pneumothorax, will also grow.
The length of time required between diving and flying depends on many factors, e.g. depth, duration and number of dives, therefore it is impossible to give a definitive pre-flying period. However, it is recommended that following SCUBA diving an individual should wait at least 12 to 24 hours before flying (Divers Alert Network).
Dehydration
This is one of the main factors in increasing the severity of DCS. In order to off-load the increased burden of inert gas from the body, a good volume of fluid in the circulatory system is needed. If a casualty is dehydrated, gas transport will be inhibited by the reduction in plasma while bubble formation and growth will be encouraged by the relative increase in density of solid matter in the blood.
As bubbles grow and combine to form larger ones, they affect the surrounding tissue making it more permeable to liquid. This results in a loss of fluid from the circulation and ever increasing dehydration. 
Dehydration should be avoided by drinking plenty of water following a dive. Drinking copiously before a dive may allow more inert gas to be absorbed which will increase the risk of DCS if the extra fluid is then lost prior to surfacing.
Alcohol
The effects of alcohol on co-ordination, consciousness and mental reasoning are well documented and have obvious implications in the ability of a diver to carry out the tasks necessary for a safe dive. This reduction in ability also applies to a 'hangover'.
Alcohol will increase the chances of developing nitrogen narcosis due to the depressant effect on the central nervous system. As with any CNS condition, intoxication following a dive will potentially mask some of the symptoms.
Alcohol is also a powerful diuretic that will increase urine output and promote dehydration.

Repetitive diving
Following each dive the body retains some of the inert gas dissolved in the tissues. The correct use of dive tables usually allows enough of the gas to be excreted via the lungs to avoid the formation of bubbles large enough to cause physiological problems.
Repeated dives will increase the risk of DCS if adequate time is not allowed to offload the dissolved gas. For the same reason, the depth and duration of the dive will influence the amount of absorbed gas.
Temperature
SCUBA diving in warm water will generally result in higher nitrogen loading than in cold water. This is due mostly to the effects of vasodilatation. Becoming cold following a dive may increase urine output and lead to dehydration. In any suspected case of DCS, the casualty must be kept warm and dry.
Obesity
An increase in adipose tissue leads to an increase in nitrogen loading in the body, since nitrogen is five times more soluble in fat tissue than muscle. Because fat can absorb more gas than muscle, it will take longer for the body to excrete it. It is generally assumed that there is a related increase in risk of decompression sickness.
Obesity also increases the body's oxygen requirements, leading to a likely reduction in physical ability. The long-term implications of obesity are well known. Conditions related to obesity such as diabetes and coronary artery disease are themselves believed to be DCS risk factors.
Exercise 
Fit, healthy individuals are less likely to suffer from most medical conditions than unfit ones but there are possible risks involved with strenuous physical exercise.
It has been suggested that strenuous exercise causes the formation in the body of tiny gas bubbles called 'micronuclei' (Dervay et al, 2002). It takes several hours for these bubbles to disperse.
Age & Gender
There are conflicting studies showing the existence, or lack, of a relationship between a diver's age / gender and the incidence of decompression sickness. A study by the Armstrong Laboratory concluded that there is a three-fold increase in high altitude DCS in men over 42 years old compared to those aged 18-21. The reason for any increased risk in dive related DCS might be due to the distribution and amount of fat in the diver's body. 
Patent Foramen Ovale (PFO)
One of the most significant predisposing risk factors in DCS is a physical abnormality of the heart called Patent Foramen Ovale (PFO) - a small opening between the upper two chambers of the heart (atria).
Every unborn baby has a Foramen Ovale that allows blood already oxygenated by the mother's lungs to by-pass the baby's respiratory system. The opening usually seals up following birth.
If it remains open (patent) then it can cause a 'short circuit' of blood flow allowing bubbles to pass directly from the venous circulation to the brain through the heart, bypassing the filtering effect of the respiratory system.
PFO is present in about 25% of the general population and does not normally cause health problems. However, it affects up to 75% of those with 'unexplained' DCS (Kerut et al, 2001).
Although PFO increases the risk of decompression sickness, individuals with PFO do not necessarily develop symptoms. Also, those who have suffered an 'unexplained' case of DCS do not always have a PFO.
Injury 
Because bubbles form more easily around physical imperfections, tissue damage (e.g. a ‘bad knee’) can lead to greater risk of bubble formation and DCS. The risk may also be increased due to localised changes in blood perfusion.
Previous DCS
Divers who have had previous occurrences of DCS are far more susceptible to the condition than those who have never had it. This is related to tissue damage caused by previous bubble formation, especially in the Central Nervous System, and pre-existing susceptibilty to the condition.
Some divers, when questioned following an incidence of DCS, reveal that they have possibly suffered ‘sub-clinical’ bends in the past – i.e. the symptoms at the time were not obviously manifested.
Smoking
Cigarette smoke contains carbon monoxide (CO), which is a poison. This reduces the ability of the red blood cells to carry oxygen. Cigarette smoke also contains nicotine, which acts as a vasoconstrictor and may theoretically increase the risk of DCS due to altered blood perfusion.
Long term problems include chronic obstructive pulmonary disease (COPD) which leads to carbon dioxide (CO2) retention. This has been implicated as a factor in CNS oxygen toxicity. Smokers are also generally less healthy and are more prone to develop circulatory problems.