The Bends: Scuba Diving Guide

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Many people have heard of ‘the bends,’ and fear of this condition may prevent some people from taking up scuba diving. The bends are a serious concern but are often misunderstood. So let’s learn more about it and clear up some misconceptions.  

What is ‘the Bends’? 

The bends is a condition known by many names. It is also called decompression sickness, diver’s disease, aerobullosis, and caisson sickness. Because decompression sickness is strongly associated with joint immobility, which can sometimes be alleviated by holding a joint in a bent position, it is known as ‘the bends.’ 

Because the bends can vary dramatically in severity and affect every part of the body, there is a wide range of signs and symptoms. However, some of the most common signs of the bends include: 

  • Musculoskeletal pain – This can be mild or severe and may be aggravated by joint motion 
  • Skin sensations – Skin may itch or tingle, swell or have a marbled appearance 
  • Neurological symptoms – A person may have confusion, mood changes, or even seizures 
  • Other signs and symptoms – Some other common signs of decompression sickness include headache or fatigue, loss of balance or vertigo, tightness in the chest, or shortness of breath.  
  • Joint pain, especially in the arms and legs – This is the most common symptom of the bends, with more severe symptoms happening in less than 10% of cases.  
the bends

What Causes the Bends? 

As a diver descends below the water, external pressure on the body increases. To compensate, divers carry an air tank that provides pressurized air to keep the chest and lungs from collapsing. This means that as external pressure on the body increases, the tank offers greater internal pressure to compensate. Under higher pressure, the natural gases in the body expand. 

Oxygen molecules expand under pressure, but oxygen is metabolized as we breathe while diving. Other naturally occurring gases, like nitrogen and helium, also become more soluble and expand but are not metabolized and can build up in the body while we dive.  

If a diver re-surfaces too quickly, these expanded gases can form bubbles inside the body, like a bottle of carbonated soda, which looks clear when sealed but creates bubbles when opened. 

In addition, accumulated nitrogen in the body can form and cause painful bubbles in the muscles and blood vessels. These bubbles are particularly noticeable in the joints, where veins and arteries are wrapped tightly around many body structures. This may cause more pressure on the joints forcing them into a bent shape and restricting the range of motion.  

The basic principle is that the deeper the dive is, the more pressure there is, and the more soluble gases build up in the body.  

How to Avoid the Bends 

The simplest way to avoid the bends is to ascend from a dive slowly, at the correct rate, allowing pressure to equalize and accumulated gases to reabsorb normally into the body.  

A large portion of scuba diver training focuses on how to safely ascend and avoid decompression sickness. However, several factors affect your chances of getting the bends that aren’t related to your actual dive at all. To dive safely and avoid decompression sickness, keep the following tips in mind. 

Remain Hydrated 

Dehydration is one of the most common risk factors for the bends because dehydration reduces blood plasma volume and reduces blood flow. This reduction in fluid volume makes it more difficult for the body to eliminate inert gases.

In normal conditions, divers are prone to dehydration due to fluid loss in sweat, urine, and lower temperatures in the water, so compensate with extra hydration for every dive.  

the bends

Keep Fit 

Improved fitness boosts your cardiovascular health, helping your body more efficiently manage oxygen and eliminate nitrogen. It also improves control and stamina during your dive, which makes every dive safer.  

Avoid Alcohol and Soda Before a Dive 

Aside from these beverages being dehydrating, alcohol can affect your heart rate as well as your judgment. So to dive safely and stick to your dive plan, it’s always best to remain sober.  

Avoid Flying and High Altitudes After Diving 

Decompression sickness often does not affect divers immediately after they finish a dive. In fact, symptoms may occur 8 or even 24 hours after completing a dive.

During the 24 hours after a dive, nitrogen is still being released and processed in the body, so it’s essential to remain at normal air pressure and avoid high altitudes.  


The bends can be painful and even dangerous in some cases, but it is easy to avoid in almost all instances. Follow your training, plan your dive, dive your plan, and ascend slowly to stay healthy and enjoy every aspect of scuba diving   

Read our Scuba Diving Salaries Guide

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