Nervous System Hacks to Make you Feel Calmer Before Your Dives

(photo credit: eyxlphoto)

If you’ve done a freediving course you’ve heard it constantly:

“Relax.”

And to be fair, instructors are right. Relaxation is the key to good dives.

But it’s also one of the least useful instructions ever given to a nervous diver… because nobody explains how.

Relaxation isn’t a personality trait. It’s not something some divers naturally have.

It is a physiological state. And like equalisation, finning, and duck-diving, it can be trained.

In this article, we are going to merge two worlds and give you some breathwork hacks, that not many people know about in freediving. These 'hacks' have come about thanks to Dr Buteyko, and more recently reiterated by James Nestor, author of Breath

Once you understand this, freediving stops feeling random.

From Being Scared of Depth To Finding My Deep Dives Easier

I’ve always had performance anxiety.

Even something simple, if someone said, “hold your breath for one minute right now,” I’d feel pressure, even though I could comfortably hold my breath five times longer. The number didn’t matter. My body reacted to the expectation.

Depth was the same.

For me it was 40 m.Every time I saw that number on the plate, my nerves spiked. I could physically do the dive, but mentally it felt like a big event. And I started asking myself a serious question:

How was I ever going to reach 50 m, 60 m, or deeper if 40 m already triggered anxiety?

So I stopped only training my lungs, and started training my brain.

I spent a lot of time visualising dives. Not vaguely, but in detail. Clipping onto the line, my breathe-up, the duck dive, the first equalisation, the freefall, reaching the plate, turning calmly, and ascending smoothly. I also used self-guided confidence hypnosis and repeatedly rehearsed successful deep dives in my head.

Here’s the interesting part.

After months of doing this, I actually felt more relaxed clipping onto the line for a 67m m dive than I used to at 40 and 50 m.

Nothing about my lungs had magically changed that day. My nervous system had.

Because my brain felt like it had already done the dive hundreds of times.

Sports psychology research shows vivid mental rehearsal activates many of the same neural pathways as physical practice. To your brain, a deeply imagined successful experience reduces uncertainty. And uncertainty is what drives the stress response.

The depth didn’t change first.

My perception of safety did.

Once my brain stopped interpreting the dive as unknown, the pre-dive adrenaline dropped, my heart rate stayed lower, equalisation became smoother, and the dives themselves actually felt easier.

The biggest barrier to deeper diving often isn’t physiology.

It’s familiarity.

Your body relaxes when your brain recognises what’s about to happen. And sometimes the safest way to teach your brain that… is to show it the dive before you ever leave the surface

Why relaxation actually matters in freediving

I know a lot of you will already know some of this, but here me out...

Relaxation directly changes your physiology underwater.

When you’re relaxed:

• You consume less oxygen

• CO₂ rises more slowly

• Heart rate drops

• The dive reflex strengthens

• Equalisation becomes easier

• Contractions feel softer

When you’re stressed:

• You burn more O2

• Your urge to breathe hits early

• Equalisation fails (soft palette closes, tongue becomes difficult to move, and tensor veli paletini locks up)

  
  

Freediving performance is largely a breathing and nervous system problem, not a lung size problem.

What Buteyko discovered (and why it matters to freedivers)

Ukrainian physician Dr. Konstantin Buteyko noticed something surprising while treating asthma patients:

People who breathed more air were often more breathless.

The key idea:

Your urge to breathe is driven mostly by CO₂, not oxygen.

Your body rarely panics because oxygen is low. It panics because carbon dioxide rises.

Freedivers feel this as contractions.

Buteyko found chronic over-breathing causes:

• anxiety

• poor breath control

• low CO₂ tolerance

• inefficient oxygen delivery

This is exactly what happens during a rushed or aggressive breathe-up.

The Bohr Effect

Carbon dioxide is not just waste gas.

It actually helps oxygen leave the blood and enter tissues.

This is the Bohr Effect:

Low CO₂ → oxygen stays attached to haemoglobin.

Higher CO₂ → oxygen releases into brain and muscles

Hence why overbreathing and hyperventilation should be avoided before your dives as it can make your body less able to use oxygen.

James Nestor’s modern findings

Modern respiratory research summarised by James Nestor shows slow nasal breathing:

• increases nitric oxide production

• improves circulation

• reduces heart rate

• improves CO₂ tolerance

• reduces anxiety

Nitric oxide matters because it:

• dilates blood vessels

• improves oxygen delivery

• improves airflow efficiency

Humming increases nitric oxide even more, which is one reason experienced divers often hum before their dives.

The two modes of your nervous system

Your body runs on the autonomic nervous system.

Sympathetic Nervous System — Survival Mode

Fight / flight / freeze.

Before a deep dive:

• heart rate rises

• thoughts race

• breathing speeds up

• equalisation becomes harder

  
  

Your brain interprets depth as danger.

This increases oxygen consumption and reduces fine motor control.

Parasympathetic Nervous System — Ideal state for diving

Rest / digest / recover.

Signs:

• slow breathing

• clear mind

• low heart rate

• easy equalisation

• “flow state” dives

It can seem like your nervous system gets away of you, but there are simple steps to help you take control of the wheel. The more you train mindset, visualise your dives, and do some of the tools I recommend below, the better your body will be at having a better baseline within the PNS.

Why equalisation improves when you calm down

Equalisation relies on coordination of:

• tongue

• soft palate

• glottis

• throat muscles

• Tensor Veli Paletini (small muscle between soft palette and eustachian tube)

Stress increases muscle tension and reduces coordination.

That’s why some divers can equalise perfectly in the pool but suddenly struggle at depth.

It’s not technique.

It’s nervous system state.

Practical nervous system tools (supported by breathing science)

The parasympathetic nervous system is largely driven by the vagus nerve, and strengthening your vagal tone improves how easily your body shifts into a calm state. Whether you use these techniques during your breathe-up or practise them daily away from the water, both approaches help condition your nervous system and you’ll notice the benefits in your diving.

1) Nasal breathing (with an important freediving tip)

Nasal breathing is one of the most powerful calming signals to the brain.

It:

• prevents over-breathing

• improves CO₂ tolerance

• promotes diaphragm breathing

• improves oxygen intake by 20%

• increases nitric oxide

The catch in freediving:

A mask restricts nasal breathing.

Many divers instinctively switch to mouth breathing once the mask is on, and this often quietly pushes the body back toward sympathetic activation.

A very useful workaround: Do the majority of your breathe-up with your mask/nose clip off and your face out of the water, breathing calmly through your nose.

Then:

• put mask on

• final 2–3 breaths through snorkel or mouth

• final breath → dive

You’re essentially using nasal breathing to activate the parasympathetic nervous system, then only using the mouth for the final ventilation phase.

Many experienced depth divers do this naturally without realising why it helps.

2) Coherent breathing (5–6 sec in, 5–6 sec out)

This breathing rhythm improves heart rate variability and vagal tone.

Effects:

• lowers heart rate

• stabilises CO₂

• prevents hyperventilation

• calms the mind

It closely matches an ideal freediving breathe-up.

3) Humming

Humming:

• stimulates the vagus nerve

• increases nitric oxide production

• reduces anxiety

• may assist equalisation

It’s a simple but extremely effective pre-dive tool.

4) The physiological sigh

Two short inhales followed by one long slow exhale. As you exhale, let your face fall soft, and eyes heavy.

This rapidly reduces stress and resets breathing control centres. Very effective right before you start your breathe-up.

5) Longer exhales

The exhale strongly activates the parasympathetic system, and heart rate lowers further. The SSI education system teach the ratio breath, at a 2:1, i.e. Inhale 4 seconds, exhale 8 seconds.

Within 1–2 minutes most divers feel noticeably calmer.

6) Face immersion

Cold water on the face activates the trigeminal nerve and mammalian dive reflex, lowering heart rate almost immediately.

Splashing your face before a dive genuinely prepares your physiology.

7) Visualisation

Your brain responds to vivid imagery almost like real experience.

If you repeatedly visualise:

• calm descent

• smooth equalisation

• relaxed ascent

your brain interprets the dive as familiar rather than threatening.

This reduces sympathetic activation significantly.

The key takeaway

Relaxation is about convincing your nervous system you are safe.

As I always teach my students, "It's easier to act your way into a new way of thinking, then to think your way into a new way of acting"...or, "FAKE it until you make it."

The best freedivers aren’t the bravest, or the most genetically gifted.

They’re the best at sending one clear message to their brain, and take control of the sterering wheel.

And once your body believes that, diving stops feeling like breath-holding…

and starts feeling like home underwater.