Diving Risks

Just like any other physical activity or sport

DH (9)recreational diving has some risks that divers must be aware of, in order to avoid them, and if need be, treat and deal with these risks in an appropriate manner. Diving risks can be divided into two categories, physiological risks and external hazards:

Physiological risks: as much fun as diving is, it’s not without a price, Extreme pressure from being under water has its toll on the body, and can lead to serious illness and even death.

These physiological dangers can be summarised in three main illnesses or risks, Decompression illness, Oxygen toxicity, and Pulmonary embolism.

Decompression sickness (DCS):

DH (8)Decompression sickness occurs when the ambient pressure around the body drops rapidly and bubbles start to form in the blood flow, the bubbles either grow in tissues and cause local damage, or enter arteries through the lungs and block the blood flow.

DCS not only affect divers, but also anyone who might be working in places with great pressure, Aviators, Astronauts, and compressed-air workers are also affected.

A number of factors increase the chances of DCS affecting divers, deep/long dives, cold water, hard exercise at depth, and rapid ascents.

It’s also suggested that Obesity, dehydration, hard exercise immediately after surfacing, and pulmonary disease, are factors that increase DCS chances, however no evidence is present that supports this at the current moment.

DH (7)DCS requires immediate treatment, but how do you know if someone has DCS?

These are the symptoms and signs that you need to keep an eye out for:


Symptoms of DCS:

Unusual fatigue

Skin itch

Pain in joints and / or muscles of the arms, legs or torso
Dizziness, vertigo, ringing in the ears

Numbness, tingling and paralysis

Shortness of breath


Signs of DCS:

Skin may show a blotchy rash

Paralysis, muscle weakness

Difficulty urinating

Confusion, personality changes, bizarre behavior



Coughing up bloody, frothy sputum

Collapse or unconsciousness

Signs and symptoms of decompression sickness

DCS type

Bubble location

Signs & symptoms (clinical manifestations)


Mostly large joints

(elbows, shoulders, hip, wrists, knees, ankles)

·        Localized deep pain, ranging from mild to excruciating. Sometimes a dull ache, but rarely a sharp pain.

·        Active and passive motion of the joint aggravates the pain.

·        The pain may be reduced by bending the joint to find a more comfortable position.

·        If caused by altitude, pain can occur immediately or up to many hours later.


Skin ·        Itching, usually around the ears, face, neck, arms, and upper torso

·        Sensation of tiny insects crawling over the skin (formication)

·        Mottled or marbled skin usually around the shoulders, upper chest and abdomen, with itching

·        Swelling of the skin, accompanied by tiny scar-like skin depressions (pitting edema)


Brain ·        Altered sensation, tingling or numbness (paresthesia), increased sensitivity (hyperesthesia)

·        Confusion or memory loss (amnesia)

·        Visual abnormalities

·        Unexplained mood or behaviour changes

·        Seizures, unconsciousness


Spinal cord ·        Ascending weakness or paralysis in the legs

·        Urinary incontinence and fecal incontinence

·        Girdling (also referred to as girdle, banding, or tightening feeling) around the abdominal region and/orchest


Whole body ·        Headache

·        Unexplained fatigue

·        Generalised malaise, poorly localised aches


Inner ear ·        Loss of balance

·        Dizzinessvertigonauseavomiting

·        Hearing loss


Lungs ·        Dry persistent cough

·        Burning chest pain under the sternum, aggravated by breathing

·        Shortness of breath

DH (5)The distribution of symptoms of DCS



local joint pain 89%
arm symptoms 70%
leg symptoms 30%
dizziness 5.3%
paralysis 2.3%
shortness of breath 1.6%
extreme fatigue 1.3%
collapse/unconsciousness 0.5%

DH (4)

Pulmonary barotrauma (PB):

DH (2)Like the two previous medical conditions, PB occurs when the pressure in the body changes rapidly, which is what would happen if a diver ascends too quickly, holding your breath while ascending is also a major factor for causing PB. As the pressure changes during the diver’s ascend, the lungs expand, if the diver holds his/her breathe, the lungs can rapture or even pop like a balloon! The lungs do not sense pain, thus little warning is given to the diver as he/she ascends to the surface, which is exactly why divers NEVER hold their breaths during a dive, especially not when ascending. The damage can differ from one diver to another, depending on the depth and the speed in which they ascended; damage can vary from chest pain, to coughing blood, or even in extreme cases, death. External hazards: Besides the physiological risks that come with diving, there are also external hazards and risks in an underwater environment, divers must be aware of and take their precautions against these risks to avoid any unpleasant underwater surprises. The two main external hazards that affect divers are faulty equipment and the marine life. Faulty equipment: It is of great importance that proper check of equipment is performed before each dive, the last you would want when submerged 30 meters underwater is a faulty regulator or pressure gage. Even if something as simple as goggles went south on you underwater, it will most certainly ruin your day and cause you to cancel your dive, it could also lead to injuries and even death!

Oxygen toxicity (OT):

DH (3)Similarly to DCS, OT occurs when the body is under great pressure, which is the usual case in deep diving. At great depths, the body absorbs more oxygen molecules than at the surface, this causes central nervous system toxicity, which leads to symptoms such as: disorientation, breathing problems, and vision changes. Extreme or long exposures to high oxygen molecules can cause damage to the cells themselves, thus, lower chances of recovery, which is why it is crucial that divers stop descending once they feel unwell or drowsy and start to ascend immediately. The greatest danger from OT lays in the convulsions that it causes, it is not clear whether these convulsions cause nervous system damage after it happens, but these convulsions could certainly lead to incidental damage, such as injuries or even drowning, as the diver cannot control his breathing when he/she is affected.

Marine life:

DH (1)Just like the wilderness of a jungle or a forest, the ocean can be full of surprises, some of which are not so pleasant. And just like a hunter in the bush, a diver must be aware of his surroundings at all times, not just to avoid harm to him/her self, but also to avoid causing damage to the environment and local marine life. One must understand that divers are in a constant danger of a nasty confrontation with the marine life, not to say that the fish are out there looking to harm divers, but the fact is, that there are numerous species of poisonous sea creatures that can cause harm from just a touch, whether it be intentional or not. In any case, you can never be too careful when it comes to diving, especially if you are diving in an unfamiliar spot.

There is also a possibility of being attacked by bigger fish, sharks for example. Yes it is rare that people get attacked by sharks, but it does happen, thus a diver must learn how to not aggregate the local marine life to avoid any and all unwelcomed encounters.

Besides the marine life, divers must also be aware of their surroundings to avoid cuts and hemorrhages, whether from rocks or corals, being cut underwater and bleeding is not something you want to experience, especially if you are a new diver!

A simple but effective countermeasure against cuts is wearing your full protective gear, such as gloves, suite, and boots. And always remember to be careful and aware of your surrounding at all time, that way you will have a injurie free dive and help preserve the environment.

Faulty equipment

DH (3)It is of great importance that proper check of equipment is performed before each dive, the last you would want when submerged 30 meters underwater is a faulty regulator or pressure gage.
Even if something as simple as goggles went south on you underwater, it will most certainly ruin your day and cause you to cancel your dive, it could also lead to injuries and even death!