Breathing as a scuba diver

  • Slow

    Breathe at a calm, steady pace.

  • Deep

    Allow the diaphragm to gently pull air deep into the lungs, without forcing them full (i.e. tidal volume).

  • Continuous

    Keep breathing, avoiding unintentional pauses or breath holding

How to Breathe Underwater

You probably remember from your training being instructed to “breathe normally” underwater. But what does that really mean?

On the surface, a normal breath, when we are in a calm and regulated state, is naturally slow and relatively deep, though not forced. The rhythm will change with exertion or stress. At rest healthy breathing tends to be unforced and steady. This is the type of breathing you want to carry into diving.

Although it is helpful advice, in practice, it is useful to go beyond "breathe normally" advice. When we tell someone to carry on breathing normally underwater, we are assuming that their "normal" breath on the surface is healthy. 

Many people develop patterns of dysregulated breathing in daily life, such as shallow chest breathing, fast breathing rates or breath-holding when stressed or distracted.  Left unchecked, this can carry over into diving. (Check out James Nestor's work: https://www.mrjamesnestor.com/.) Underwater, these habits can reduce comfort, efficiency, and control. Fast breathing increases stress.  Shallow breathing means inefficient gas exchange (i.e. most of the air/gas never gets to the lungs before it is exhaled out of the regulator). Unconscious breath holding can be dangerous, for example leading to positive buoyancy, rapid ascent and risk of lung barotrauma.

This is why dive training agencies and diver medical websites emphasise that effective diving breath is:

  • Slow and steady

  • Deep, though not forced

  • Continuous (not breath-holding)

Of course, during exertion your breathing rate will rise and that is the body's way of increasing oxygen intake to fuel your movement. Here it can be useful to have some awareness of breath, recognising when it becomes rapid or shallow, making adjustments (e.g. slowing movement if appropriate) and gently guiding it back to a calmer rhythm when conditions allow.

For divers, the most effective way to improve breathing is not necessarily to start underwater, but to build better breathing habits on the surface. By practising slow, steady, diaphragmatic breathing in everyday life, divers can carry those habits into their diving, where they support comfort, gas efficiency, buoyancy, and emotional regulation.

Tidal Volume and Deep Breaths

Respiration is a huge, complex topic. If you want to learn more about lung volume and capacity, here is a video.  For a broader overview of breathing and respiration, from mouth/nose through lungs and into cells, in scuba diving, Mark Powell's book"Deco for Divers" is useful. This article gets into some of the complexities of breathing and diving. If you are healthy and happy to try the following, learn about some of the basics using your own breath ...

Take a moment right now. Stop and notice how you are breathing. If you’re in a relatively relaxed state, what you’ll probably be doing is breathing in and breathing out about the same amount, unforced, quietly. Your ribs move some, your diaphragm moves some, so that air is moving relatively deep into the body. There’s a gentle rhythm.

Definition of tidal volume:

“Tidal volume is the amount of air that moves in or out of the lungs with each respiratory cycle during restful breathing.” https://www.ncbi.nlm.nih.gov/books/NBK482502/


Now try this: take a big breath, a really full breath. See if you can fill your lungs more fully than your usual breath. Notice how it feels different from your natural breathing.

When we dive, we generally want our breathing to look more like that natural deep(ish) breathing: relaxed, enough of a breath, involving diaphragm and lower ribs. This is because very shallow breaths may not move air efficiently into the lower parts of the lungs.


Deep breath vs Big breath:

  • Deep breath means air coming down into the lower lungs rather than shallow chest-only movement. It doesn’t mean you try to force in every last drop.

  • Big breath is trying to fill up the lungs with air (which can be unsustainable and, in scuba diving can cause us to use air more quickly as well as move up and down on each breath!).

If you’re still uncertain about the difference, there’s a short course Deep Breathing for Scuba Divers that goes into this in more detail, sign up using the link below.


Poor Breathing Habits

For some (perhaps many) of us, breathing can become habitually shallow, so that our tidal volume gets to be a bit less. Breathing rate can also increase, so that there is less time to exchange gas in the lungs.  Periods of stress or lack of physical activity can do this.  

If this is the case, attempting deeper, slower breaths than is normal for when underwater may create issues. For example, really focusing on breathing alot can be distracting and sometimes cause stress. That's one reason instructors will tell new divers to breathe normally underwater.

It's possible, and fairly straightforward to improve breathing habits on the surface, gradually regaining slower, deeper breaths with a decent volume.

7 Reasons

Breathing Practices for Scuba Diving

  • AIR/GAS CONSUMPTION Slow, steady breathing makes more efficient use of your gas supply, helping extend dive time and reduce the risk of running low.

  • BUOYANCY CONTROL On open-circuit scuba, every breath changes lung volume and buoyancy. A calm rhythm supports stability and smoother control in the water.

  • EMOTION REGULATION Breathing patterns directly influence the nervous system. Maintaining a steady rhythm helps manage stress and lowers the risk of panic.

  • PREVENTION OF CARBON DIOXIDE BUILD-UP Incomplete exhalation can lead to excess carbon dioxide, causing headaches, anxiety, or confusion. Exhalations help keep carbon dioxide levels in check.

  • WORKLOAD AND EXERTION Efficient breathing ensures the body gets the oxygen it needs during exertion. While divers aim to avoid overexertion, controlled breathing helps the body cope better when effort is unavoidable.

  • DECOMPRESSION SAFETY Breathing with continuous rhythm, avoiding unintentional breath holding, is especially important during ascent. This helps protect against pulmonary barotrauma and supports safe ascent practices.

  • AWARENESS OF BREATH Developing mindful awareness of breathing means noticing changes, such as faster or shallower breaths and being able to respond. Without this awareness, signs of stress, CO₂ build-up, or overexertion may go unnoticed.

Breathing Practices You Can Try

These practices are designed for the surface, not underwater. They’re intended to help you develop control, awareness, and efficiency in your breathing habits. Try them in a safe, comfortable place where you can sit or lie down without distraction.

1. Counting Breaths (for rhythm and control)

Counting your breath is a way to regulate the length of your inhale and exhale, and sometimes add short pauses. The numbers don’t matter as much as keeping a consistent rhythm.

  • Sit upright or lie down comfortably.

  • Inhale gently through your nose for a slow count (e.g. 4).

  • Pause for the same count (if you’re doing box breathing), or adjust for longer exhalation (e.g. 4 in, 6 out).

  • Exhale steadily through your mouth or nose for the chosen count.

  • If using box breathing, add another pause before the next inhale.

  • Continue for 6–8 cycles, noticing the steady rhythm.

Variations:

  • Box Breathing: Equal inhale, hold, exhale, hold (e.g. 4-4-4-4).

  • Rectangle Breathing: Longer exhale than inhale (e.g. 4-2-6-2).

  • 4-7-8 Breathing: Inhale, Hold, Long Exhale.



2. Mindful Awareness of Breath (for focus and calm)

This practice builds awareness of your natural breathing, without trying to change it. It’s a foundation for noticing your breath in diving and everyday life.

  • Sit comfortably with your back supported.

  • Close your eyes if that feels safe.

  • Bring your attention to the sensation of breathing — the air at the tip of your nose, your chest or belly rising and falling.

  • Notice the inhale… notice the exhale… without adjusting it.

  • If your mind wanders, gently bring it back to the breath.

  • Try this for 2–5 minutes, gradually extending with practice.

The aim is not to control the breath, but to notice it. This awareness makes it easier to recognise changes in your breathing when diving.


3. Diaphragmatic Breathing (for depth and efficiency)

This exercise trains you to use your diaphragm — the main breathing muscle — rather than shallow chest breathing.

  • Sit or lie down comfortably.

  • Place one hand on your chest and the other on your belly.

  • Inhale gently through your nose, aiming to move your belly hand more than your chest hand.

  • Exhale slowly, letting the belly fall back.

  • Keep shoulders relaxed and avoid lifting them as you breathe.

  • Continue for 5–10 breaths, noticing the fuller, calmer rhythm.

Over time, this becomes more natural and helps ensure each breath draws air deeper into the lungs.

Deep Breathing for Scuba Divers

Not sure how to do diaphragmatic breathing, take this short course with a scuba diving instructor/psychologist!

More Reading

Articles about breathing and air consumption in scuba diving

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