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 (AKA "tidal breathing"). 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). Unconcious 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 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.