Scuba Diving Bends:

What is Decompression Illness?

The scuba diving bends is what most divers probably think about when they think of dive illnesses or accidents.

Better known simply as "the bends" or decompression illness (dci for short), it is something we all want to avoid.

According to Divers Alert Network (DAN), approximately 1,000 U.S. scuba divers suffer from the bends each year so it is not an uncommon occurrence.

What are the Scuba Diving Bends or Decompression Illness (DCI)?

"The bends" is the illness that results from nitrogen bubbles being formed in your blood stream and/or tissues.

It is caused by decreasing pressure too quickly after a period of increased pressure (such as ascending too quickly after a dive).

It gets its name from the fact that nitrogen bubbles may form in or near the joints, causing pain and causing the diver to "bend over".

What Causes the Scuba Diving Bends or Decompression Illness?

The main cause of the bends is a change in pressure and what this does to the nitrogen in our body.

The air in a standard scuba tank (this excludes nitrox diving) is comprised of 79% nitrogen and 21% oxygen.

As we descend, pressure increases. Thus the nitrogen in our tanks will increase in pressure as we go deeper.

Scuba diving cartoon on the bends or decompression illness


Our body tissue absorbs the nitrogen we are breathing from the air in our tanks in proportion to the surrounding pressure. So the deeper we go and the more pressure being exerted, the more nitrogen our tissues will absorb to maintain equilibrium.

The longer and deeper the dive, the more nitrogen is absorbed by our bodies. As long we we remain under pressure there is no problem.

The problem occurs when we begin to ascend and the pressure begins to decrease. Since we are decreasing the pressure as we ascend, our body wants to decrease the amount of nitrogen in our system to maintain equilibrium.

Since the body does not metabolize this nitrogen, we must somehow get rid of it.

The classic example of explaining what the bends is and how it occurs is to picture a bottle of soda (or bottle of beer). If you slowly open the cap and let the pressure off at a slow rate, the contents in the bottle won't form bubbles and fizz all over.

However, if you quickly take the cap off the bottle, the liquid will form bubbles and come spouting out of the bottle (and who hasn't had a bottle of beer fizz over the top?).

This is exactly what happens to the nitrogen in our bodies as we ascend after a dive.

We are decreasing pressure and the nitrogen is released from our tissues into our bloodstream. It then reaches our lungs and is exhaled as we breathe.

Letting the nitrogen out at a safe rate is what is key for the diver. If we ascend too quickly, the body won't be able to expel all the nitrogen and bubbles will form in our tissue and bloodstream.

Emergency room sign


So we have to slowly decrease the pressure so our bodies have time to safely expel the nitrogen without forming bubbles. Just like that bottle of soda (or beer if you will).

This is the reason why a slow, controlled ascent is so important in scuba diving. You are letting the body get rid of the accumulated nitrogen.

It is also the reason why every non-decompression dive should end with at least a 3 minute safety stop and the next dive should never begin before an appropriate surface interval.



 Want to stay down longer and improve your buoyancy control and other diving skills? Our free report "Increase Your Bottom Time" along with our practical, weekly actionable tips will have you looking like a seasoned diver in no time. So come join us and see improvement on your very next dive!
(Click on the photo to join us now!)


New! Comments

Have your say about what you just read! Leave me a comment in the box below.

What's New

  1. Quick Scuba Diving Video Tip On Buoyancy Control - What Not To Use

    Sep 13, 19 06:00 AM

    scuba diving video tip on buoyancy control This quick video tip for beginner divers is all about buoyancy control. One of the areas that gives new divers some trouble. On today's tip I talk about what not to use to control your buoyancy. Onc…

    Read More

  2. Make Friends On the Dive Boat Following This Quick Scuba Diving Video Tip

    Sep 06, 19 07:00 AM

    scuba diving video tip on boat diving In today's scuba diving video tip for beginner divers, I discuss a tip about what to do when on a dive boat. Boat diving can be intimidating but knowing what to do can make you feel more comfortabl…

    Read More

  3. Quick Scuba Diving Video Tip On Air Consumption: Don't Do What I Did!

    Aug 30, 19 05:00 AM

    scuba diving video tip on air consumption Air consumption is one of the most common areas of concern for beginner divers. In today's quick video tip, I address a way to reduce your air consumption when you hit a certain condition underwate…

    Read More

  4. All Our Scuba Diving Tips

    Aug 23, 19 10:06 AM

    If you have been following me for awhile, you know I have recently been adding to our library of scuba diving tips for beginner divers - especially quick video tips. However, I have to admit that I wa…

    Read More

  5. 10 Best Scuba Diving Websites Worth Diving Into; Scuba News & Articles

    Aug 16, 19 07:47 AM

    There are lots of scuba diving websites out there - including our own. But which are worth your time? Our picks for the top 10 best dive websites to get lost in

    Read More

Top of Scuba Diving Bends

Back to main Dive Information Page

CONNECT WITH US ON FB!

scuba diving gift ideas

Our Full Dive Course

Scuba diving ebook course

Buoyancy Control

buoyancy control ebook

Air Consumption

air consumption ebook

Boat Diving

Boat diving ebook

Ear Equalization

See our choices for the best scuba equipment for any budget.